media: gspca: cpia1: shift-out-of-bounds in set_flicker

In the Linux kernel, the following vulnerability has been resolved:

media: gspca: cpia1: shift-out-of-bounds in set_flicker

Syzkaller reported the following issue:

UBSAN: shift-out-of-bounds in drivers/media/usb/gspca/cpia1.c:1031:27

shift exponent 245 is too large for 32-bit type 'int'

When the value of the variable "sd->params.exposure.gain" exceeds the

number of bits in an integer, a shift-out-of-bounds error is reported. It

is triggered because the variable "currentexp" cannot be left-shifted by

more than the number of bits in an integer. In order to avoid invalid

range during left-shift, the conditional expression is added.