powerpc/64e: Tie PPC_BOOK3E_64 to PPC_FSL_BOOK3E

Since the IBM A2 CPU support was removed, see commit
fb5a5157 ("powerpc: Remove platforms/wsp and associated pieces"),
the only 64-bit Book3E CPUs we support are Freescale (NXP) ones.

However our Kconfig still allows configurating a kernel that has 64-bit
Book3E support, but no Freescale CPU support enabled. Such a kernel
would never boot, it doesn't know about any CPUs.

It also causes build errors, as reported by lkp, because
PPC_BARRIER_NOSPEC is not enabled in such a configuration:

  powerpc64-linux-ld: arch/powerpc/net/bpf_jit_comp64.o:(.toc+0x0):
  undefined reference to `powerpc_security_features'

To fix this, force PPC_FSL_BOOK3E to be selected whenever we are
building a 64-bit Book3E kernel.
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220304061222.2478720-1-mpe@ellerman.id.au

arch/powerpc/platforms/Kconfig.cputype

@@ -107,6 +107,7 @@ config PPC_BOOK3S_64
 
 config PPC_BOOK3E_64
 	bool "Embedded processors"
+	select PPC_FSL_BOOK3E
 	select PPC_FPU # Make it a choice ?
 	select PPC_SMP_MUXED_IPI
 	select PPC_DOORBELL
@@ -295,7 +296,7 @@ config FSL_BOOKE
 config PPC_FSL_BOOK3E
 	bool
 	select ARCH_SUPPORTS_HUGETLBFS if PHYS_64BIT || PPC64
-	select FSL_EMB_PERFMON
+	imply FSL_EMB_PERFMON
 	select PPC_SMP_MUXED_IPI
 	select PPC_DOORBELL
 	select PPC_KUEP