media: staging/atomisp: make six local functions static to appease sparse

The functions __bo_alloc, __bo_search_and_remove_from_free_rbtree,
__bo_search_by_addr, __bo_search_by_addr_in_range, __bo_break_up and
__bo_merge  are local to the source and do not need to be in the global
scope, so make them static.

Cleans up sparse warnings:

warning: symbol '__bo_alloc' was not declared. Should it be static?
warning: symbol '__bo_search_and_remove_from_free_rbtree' was not declared. Should it be static?
warning: symbol '__bo_search_by_addr' was not declared. Should it be static?
warning: symbol '__bo_search_by_addr_in_range' was not declared. Should it be static?
warning: symbol '__bo_break_up' was not declared. Should it be static?
warning: symbol '__bo_merge' was not declared. Should it be static?

Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>