lib/genalloc.c: add genpool range check function

lib/genalloc.c: add genpool range check function

After allocating an address from a particular genpool, there is no good
way to verify if that address actually belongs to a genpool.  Introduce
addr_in_gen_pool which will return if an address plus size falls
completely within the genpool range.

Signed-off-by: Laura Abbott <[email protected]>
Acked-by: Will Deacon <[email protected]>
Reviewed-by: Olof Johansson <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: David Riley <[email protected]>
Cc: Ritesh Harjain <[email protected]>
Cc: Russell King <[email protected]>
Cc: Thierry Reding <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>