ARM: pxa: don't select GPIO_SYSFS for MIOA701

GPIO_SYSFS is a common kernel functionality, not something
that a board specific Kconfig should have to worry about.
In MIOA701, we get a warning about the select when CONFIG_SYSFS
is disabled:

warning: (MACH_MIOA701) selects GPIO_SYSFS which has unmet direct dependencies (GPIOLIB && SYSFS)

This just removes the select and instead enables the symbol in
the defconfig file.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>