media: sun4i-csi: Use CSI_INT_STA_REG name, fix typo in a comment

Fix interrupt status register offset usage to be a defined name
CSI_INT_STA_REG (= 0x34) instead of a plain number.

Additionally fix a typo in a comment of the same file.

Signed-off-by: Oleg Verych <olecom@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>