[media] OMAP_VOUT: CLEANUP: Move generic functions and macros to common files

Move the inline functions rotate_90_or_270(), rotation_enabled(), and
calc_rotation() from omap_vout.c to omap_voutdef.h.

Move the independent functions omap_vout_alloc_buffer() and
omap_vout_free_buffer() to omap_voutlib.c.

Remove extern identifier from function definitions in omap_voutlib.h

Add static identifier to functions that are used locally in omap_vout.c

Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>