powerpc/configs: Drop no longer needed CONFIG_SMP for pseries/ppc64/powernv

In commit 40e27565 ("powerpc/powernv: Always enable SMP when
building powernv") and 270e2dc9 ("powerpc/pseries: Always enable
SMP when building pseries") we forced CONFIG_SMP on for some configs.
Therefore we don't need to set it in those configs anymore.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/configs/powernv_defconfig

 CONFIG_PPC64=y
-CONFIG_SMP=y
 CONFIG_NR_CPUS=2048
 CONFIG_CPU_LITTLE_ENDIAN=y
 CONFIG_SYSVIPC=y

arch/powerpc/configs/ppc64_defconfig

 CONFIG_PPC64=y
-CONFIG_SMP=y
 CONFIG_SYSVIPC=y
 CONFIG_POSIX_MQUEUE=y
 CONFIG_IRQ_DOMAIN_DEBUG=y

arch/powerpc/configs/pseries_defconfig

 CONFIG_PPC64=y
-CONFIG_SMP=y
 CONFIG_NR_CPUS=2048
 CONFIG_SYSVIPC=y
 CONFIG_POSIX_MQUEUE=y