arch/powerpc/cpu/mpc8xxx/: sparse fixes

ctrl_regs.c:31:5: warning: symbol 'fsl_ddr_get_version' was not declared. Should it be static?
cpu.c:135:14: warning: non-ANSI function declaration of function 'cpu_mask'
cpu.c:154:18: warning: non-ANSI function declaration of function 'cpu_numcores'
cpu.c:37:17: warning: symbol 'cpu_type_list' was not declared. Should it be static?
cpu.c:117:17: warning: symbol 'cpu_type_unknown' was not declared. Should it be static?
fsl_lbc.c:14:6: warning: symbol '__lbc_sdram_init' was not declared. Should it be static?

and:

lc_common_dimm_params.c:15:1: warning: symbol 'compute_cas_latency_ddr3' was not declared. Should it be static?

making it static produces the following compiler warning:

lc_common_dimm_params.c:15:1: warning: 'compute_cas_latency_ddr3' defined but not used [-Wunused-function]

so we protect it with the preprocessor.

Signed-off-by: Kim Phillips <kim.phillips@freescale.com>