ARM: mach-shmobile: Tidy up the Kconfig bits.

ARM: mach-shmobile: Tidy up the Kconfig bits.

Presently each one of the CPUs manually selects the same feature set, and
there's a reasonable expectation that none of these will change for
future CPUs in the SH-Mobile / R-Mobile family, so we move those over to
the top-level ARCH_SHMOBILE.

While we're at it, all of the CPUs support optional GPIOs via the PFC,
do not have I/O ports, and expect sparse IRQ, so we bring the
configuration in line across the board.

This more or less brings the ARM-based parts in sync with their SH
counterparts.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>