powerpc/mpc83xx: sparse fixes

fdt.c:91:78: warning: Using plain integer as NULL pointer
fdt.c:103:78: warning: Using plain integer as NULL pointer
speed.c:55:11: warning: symbol 'corecnf_tab' was not declared. Should it be static?
speed.c:519:5: warning: symbol 'do_clocks' was not declared. Should it be static?
mpc8313erdb.c:73:17: warning: obsolete struct initializer, use C99 syntax
mpc8313erdb.c:74:17: warning: obsolete struct initializer, use C99 syntax
mpc8313erdb.c:75:17: warning: obsolete struct initializer, use C99 syntax
mpc8313erdb.c:76:17: warning: obsolete struct initializer, use C99 syntax
mpc8313erdb.c:79:17: warning: obsolete struct initializer, use C99 syntax
mpc8313erdb.c:80:17: warning: obsolete struct initializer, use C99 syntax
mpc8313erdb.c:81:17: warning: obsolete struct initializer, use C99 syntax
mpc8313erdb.c:82:17: warning: obsolete struct initializer, use C99 syntax
mpc8313erdb.c:85:17: warning: obsolete struct initializer, use C99 syntax
mpc8313erdb.c:86:17: warning: obsolete struct initializer, use C99 syntax
mpc8313erdb.c:87:17: warning: obsolete struct initializer, use C99 syntax
mpc8313erdb.c:88:17: warning: obsolete struct initializer, use C99 syntax

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