drivers/memstick/core/mspro_block.c: fix attributes array allocation

attrs field of attribute_group structure is a pointer to a pointer (as in
an array of pointers) rather than pointer to attribute struct (as in an
array of structures), so when allocating size of the pointer sholud be
used instead of the structure it is pointing to.

While at it, also change the call to use kcalloc rather than kzalloc.

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>