HFSPlus: change kmalloc/memset to kzalloc

Removed kmalloc and memset in favor of kzalloc.

To explain the HFSPLUS_SB() macro in the removed memset call:

hfsplus_fs.h:#define HFSPLUS_SB(super)  (*(struct hfsplus_sb_info *)(super)->s_fs_info)

Signed-off-by: Wyatt Banks <wyatt@banksresearch.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>