sh: Have SH7724 select ARCH_SHMOBILE.

This is an SH-Mobile CPU, so select ARCH_SHMOBILE. This enables all of
the PM functionality, amongst other things.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/Kconfig

@@ -351,6 +351,7 @@ config CPU_SUBTYPE_SH7724
 	bool "Support SH7724 processor"
 	select CPU_SH4A
 	select CPU_SHX2
+	select ARCH_SHMOBILE
 	select ARCH_SPARSEMEM_ENABLE
 	select SYS_SUPPORTS_CMT
 	help