powerpc/configs: Add CONFIG_NR_CPUS to ppc64_defconfig

CONFIG_NR_CPUS is not set in ppc64_defconfig, So it gets default of 32
which is quite small for modern powerpc systems. Instead set a default
of 2048 like other powerpc defconfigs.
Signed-off-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/configs/ppc64_defconfig

@@ -16,6 +16,7 @@ CONFIG_BPF_SYSCALL=y
 # CONFIG_COMPAT_BRK is not set
 CONFIG_PROFILING=y
 CONFIG_PPC64=y
+CONFIG_NR_CPUS=2048
 CONFIG_PPC_SPLPAR=y
 CONFIG_DTL=y
 CONFIG_SCANLOG=m