checkpatch: add test for char * arrays that could be static const

static const char* arrays create smaller text as each function call does
not have to populate the array.

Emit a warning when char *arrays aren't static const and the array is
not apparently global by being declared in the first column.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>