V4L/DVB (5019): Fix the frame->grabstate update in read() entry point.
V4L/DVB (5019): Fix the frame->grabstate update in read() entry point.

The Coverity checker spotted that in usbvision_v4l2_read(), the variable
"frmx" is never assigned any value different from -1, but it's used an 
an array index in "usbvision->frame[frmx]".
Thanks to Adrian Bunk <bunk@stusta.de> for warning about that.

Signed-off-by: Thierry MERLE <19404bbcc71a55fa4c9f5c68eb13c58fdc74f285@free.fr>
Signed-off-by: Mauro Carvalho Chehab <ad86ba2154032c9f55743a190faa2459a9d61d42@infradead.org>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs