This patch fixes the following build warning by allocating
a block of virtual memory to cache an instance of the structure
mxc_vout_output instead of using the stack frame.
drivers/media/platform/mxc/output/mxc_vout.c: In function ‘mxc_vidioc_s_crop’:
drivers/media/platform/mxc/output/mxc_vout.c:1529:1: warning: the frame size of 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=]