[v3] usb: xhci: remove the code build warning

Initialize the 'err' variate to remove the build warning,
the warning is shown as below:

drivers/usb/host/xhci-tegra.c: In function 'tegra_xusb_mbox_thread':
drivers/usb/host/xhci-tegra.c:552:6: warning: 'err' may be used uninitialized in this function [-Wuninitialized]
drivers/usb/host/xhci-tegra.c:482:6: note: 'err' was declared here

Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
Acked-by: Thierry Reding <treding@nvidia.com>
---
change since v1:
1. Add 'Acked-by: Thierry Reding <treding@nvidia.com>'

How to reproduce:
1. make defconfig ARCH=arm
2. make -j100 CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm

Then you can see below warnings:
drivers/usb/host/xhci-tegra.c: In function 'tegra_xusb_mbox_thread':
drivers/usb/host/xhci-tegra.c:552:6: warning: 'err' may be used uninitialized in this function [-Wuninitialized]
drivers/usb/host/xhci-tegra.c:482:6: note: 'err' was declared here
---
 drivers/usb/host/xhci-tegra.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

On 17/06/18 03:30, Dongjiu Geng wrote:
> Initialize the 'err' variate to remove the build warning,
> the warning is shown as below:
> 
> drivers/usb/host/xhci-tegra.c: In function 'tegra_xusb_mbox_thread':
> drivers/usb/host/xhci-tegra.c:552:6: warning: 'err' may be used uninitialized in this function [-Wuninitialized]
> drivers/usb/host/xhci-tegra.c:482:6: note: 'err' was declared here
> 
> Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
> Acked-by: Thierry Reding <treding@nvidia.com>
> ---
> change since v1:
> 1. Add 'Acked-by: Thierry Reding <treding@nvidia.com>'
> 
> How to reproduce:
> 1. make defconfig ARCH=arm
> 2. make -j100 CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm
> 
> Then you can see below warnings:
> drivers/usb/host/xhci-tegra.c: In function 'tegra_xusb_mbox_thread':
> drivers/usb/host/xhci-tegra.c:552:6: warning: 'err' may be used uninitialized in this function [-Wuninitialized]
> drivers/usb/host/xhci-tegra.c:482:6: note: 'err' was declared here
> ---
>  drivers/usb/host/xhci-tegra.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
> index a8c1d07..d50549f 100644
> --- a/drivers/usb/host/xhci-tegra.c
> +++ b/drivers/usb/host/xhci-tegra.c
> @@ -481,7 +481,7 @@ static void tegra_xusb_mbox_handle(struct tegra_xusb *tegra,
>  	unsigned long mask;
>  	unsigned int port;
>  	bool idle, enable;
> -	int err;
> +	int err = 0;
>  
>  	memset(&rsp, 0, sizeof(rsp));

Acked-by: Jon Hunter <jonathanh@nvidia.com>

Cheers!
Jon