ARC: add asm/gpio.h to fix compilation error with CONFIG_CMD_GPIO

With CONFIG_CMD_GPIO compilation reports error:
-------------------------->8---------------------
common/cmd_gpio.c:13:22: fatal error: asm/gpio.h: No such file or directory
 #include <asm/gpio.h>
                      ^
-------------------------->8---------------------

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>