ARM: shmobile: fix smp build

ARM: shmobile: fix smp build

I got build errors with the new version now because machine_is_kzm9g is no longer
defined:

arch/arm/mach-shmobile/platsmp.c: In function 'shmobile_smp_get_core_count':
arch/arm/mach-shmobile/platsmp.c:29:2: error: implicit declaration of function 'of_machine_is_compatible'

Replace the missing function with a call to of_machine_is_compatible.

Signed-off-by: Arnd Bergmann <[email protected]>
Acked-by: "Rafael J. Wysocki" <[email protected]>
Acked-by: Magnus Damm <[email protected]>