[media] media: am437x: fix sparse warnings

This patch fixes following spare warnings:

drivers/media/platform/am437x/am437x-vpfe.c:66:28: warning: symbol 'vpfe_standards' was not declared. Should it be static?
drivers/media/platform/am437x/am437x-vpfe.c:2202:57: warning: incorrect type in argument 2 (different address spaces)
drivers/media/platform/am437x/am437x-vpfe.c:2202:57:    expected void [noderef] <asn:1>*params
drivers/media/platform/am437x/am437x-vpfe.c:2202:57:    got void *param
include/linux/spinlock.h:364:9: warning: context imbalance in 'vpfe_start_streaming' - unexpected unlock

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>