[MIPS] rtlx: fix int vs. long bug.

  CC      arch/mips/kernel/rtlx.o
arch/mips/kernel/rtlx.c: In function 'rtlx_init':
arch/mips/kernel/rtlx.c:114: warning: format '%x' expects type 'unsigned int', but argument 3 has type 'long unsigned int'

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>