ARM: 7991/1: sa1100: fix compile problem on Collie

Due to a problem in the MFD Kconfig it was not possible to
compile the UCB battery driver for the Collie SA1100 system,
in turn making it impossible to compile in the battery driver.
(See patch "mfd: include all drivers in subsystem menu".)

After fixing the MFD Kconfig (separate patch) a compile error
appears in the Collie battery driver due to the <mach/collie.h>
implicitly requiring <mach/hardware.h> through <linux/gpio.h>
via <mach/gpio.h> prior to commit
40ca061b

 "ARM: 7841/1: sa1100: remove complex GPIO interface".

Fix this up by including the required header into
<mach/collie.h>.

Cc: stable@vger.kernel.org
Cc: Andrea Adami <andrea.adami@gmail.com>
Cc: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>