target-mips: fix get_physical_address() #if 0 build error

In get_physical_address() is a qemu_log() call inside an #if 0 block.
When enabled the following build error is hit:

target-mips/helper.c In function ‘get_physical_address’:
target-mips/helper.c:220:13: error: format ‘%x’ expects argument of type ‘unsigned int’, but argument 5 has type ‘hwaddr’ [-Werror=format]

Fix the *physical (hwaddr) formatting by using "%"HWADDR_PRIx instead of
TARGET_FMT_lx.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Yongbok Kim <yongbok.kim@imgtec.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>