hw/timer/mt48t59: Fix bit-rotten NVRAM_PRINTF format strings

hw/timer/mt48t59: Fix bit-rotten NVRAM_PRINTF format strings

When compiling with NVRAM_PRINTF enabled, gcc currently bails out with:

  CC      hw/timer/m48t59.o
  CC      hw/timer/m48t59-isa.o
hw/timer/m48t59.c: In function ‘NVRAM_writeb’:
hw/timer/m48t59.c:460:5: error: format ‘%x’ expects argument of type ‘unsigned int’, but argument 3 has type ‘hwaddr’ [-Werror=format=]
     NVRAM_PRINTF("%s: 0x%08x => 0x%08x\n", __func__, addr, val);
     ^
hw/timer/m48t59.c:460:5: error: format ‘%x’ expects argument of type ‘unsigned int’, but argument 4 has type ‘uint64_t’ [-Werror=format=]
hw/timer/m48t59.c: In function ‘NVRAM_readb’:
hw/timer/m48t59.c:492:5: error: format ‘%x’ expects argument of type ‘unsigned int’, but argument 3 has type ‘hwaddr’ [-Werror=format=]
     NVRAM_PRINTF("%s: 0x%08x <= 0x%08x\n", __func__, addr, retval);

Fix it by using the correct format strings and while we're at it,
also change the definition of NVRAM_PRINTF so that this can not
bit-rot so easily again.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>