staging: wilc1000: rename Handle_GetMacAddress function

This patch renames Handle_GetMacAddress function to handle_get_mac_address
to avoid camelcase.

Signed-off-by: Leo Kim <leo.kim@atmel.com>
Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>