staging: wilc1000: handle_set_mac_address: remove debug message of kmalloc failure

There is no need to print debug message when kmalloc is failed. This
message is redundant. The code already show us that kmalloc is failed.
The brace of if statement is remove as well due to have a single
statement.

Signed-off-by: Chaehyun Lim <chaehyun.lim@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>