powerpc: Remove unused remnants from A2 cpu

Support for the A2 cpu was removed in commit fb5a5157 ("powerpc:
Remove platforms/wsp and associated pieces"), and the externs:
__setup_cpu_a2 and __restore_cpu_a2 are still around and unused, so
remove them.
Signed-off-by: Rashmica Gupta <rashmicy@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/cputable.c

@@ -63,7 +63,6 @@ extern void __setup_cpu_745x(unsigned long offset, struct cpu_spec* spec);
 extern void __setup_cpu_ppc970(unsigned long offset, struct cpu_spec* spec);
 extern void __setup_cpu_ppc970MP(unsigned long offset, struct cpu_spec* spec);
 extern void __setup_cpu_pa6t(unsigned long offset, struct cpu_spec* spec);
-extern void __setup_cpu_a2(unsigned long offset, struct cpu_spec* spec);
 extern void __restore_cpu_pa6t(void);
 extern void __restore_cpu_ppc970(void);
 extern void __setup_cpu_power7(unsigned long offset, struct cpu_spec* spec);
@@ -72,7 +71,6 @@ extern void __setup_cpu_power8(unsigned long offset, struct cpu_spec* spec);
 extern void __restore_cpu_power8(void);
 extern void __setup_cpu_power9(unsigned long offset, struct cpu_spec* spec);
 extern void __restore_cpu_power9(void);
-extern void __restore_cpu_a2(void);
 extern void __flush_tlb_power7(unsigned int action);
 extern void __flush_tlb_power8(unsigned int action);
 extern void __flush_tlb_power9(unsigned int action);