drivers/char/mspec.c: use {k,v}zalloc to allocate memory

Let memory allocator initialize the allocated memory as null, thus remove
the use of memset.

Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>