drivers/mmc/mmc.c: sparse fixes

mmc.c:137:5: warning: symbol 'mmc_send_cmd' was not declared. Should it be static?
mmc.c:203:5: warning: symbol 'mmc_send_status' was not declared. Should it be static?
mmc.c:247:5: warning: symbol 'mmc_set_blocklen' was not declared. Should it be static?
mmc.c:440:5: warning: symbol 'mmc_read_blocks' was not declared. Should it be static?
mmc.c:510:5: warning: symbol 'mmc_go_idle' was not declared. Should it be static?
mmc.c:532:1: warning: symbol 'sd_send_op_cond' was not declared. Should it be static?
mmc.c:597:5: warning: symbol 'mmc_send_op_cond' was not declared. Should it be static?
mmc.c:661:5: warning: symbol 'mmc_send_ext_csd' was not declared. Should it be static?
mmc.c:683:5: warning: symbol 'mmc_switch' was not declared. Should it be static?
mmc.c:705:5: warning: symbol 'mmc_change_freq' was not declared. Should it be static?
mmc.c:775:5: warning: symbol 'sd_switch' was not declared. Should it be static?
mmc.c:796:5: warning: symbol 'sd_change_freq' was not declared. Should it be static?
mmc.c:935:6: warning: symbol 'mmc_set_ios' was not declared. Should it be static?
mmc.c:953:6: warning: symbol 'mmc_set_bus_width' was not declared. Should it be static?
mmc.c:1108:26: warning: dubious: !x & y
mmc.c:960:5: warning: symbol 'mmc_startup' was not declared. Should it be static?
mmc.c:1243:5: warning: symbol 'mmc_send_if_cond' was not declared. Should it be s

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