Staging: rtl8188eu: replace kzalloc and memcpy by kmemdup

This was generated by 'make coccicheck' using scripts at
scripts/coccinelle/api/memdup.cocci.

Signed-off-by: Niranjan Dighe <niranjan.dighe@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>