drivers/net/rtl8139.c: Fix GCC 4.6 build warnings

drivers/net/rtl8139.c: Fix GCC 4.6 build warnings

Fix:
rtl8139.c: In function 'rtl8139_probe':
rtl8139.c:256:15: warning: variable 'fullduplex' set but not used
[-Wunused-but-set-variable]
rtl8139.c:256:6: warning: variable 'speed10' set but not used
[-Wunused-but-set-variable]
rtl8139.c: In function 'rtl_transmit':
rtl8139.c:419:16: warning: variable 'txstatus' set but not used
[-Wunused-but-set-variable]

Change code to use new debug macros; also fix the new errors and
warnigns popping up now, like "error: 'to' undeclared" and some
"warning: format '%X' expects argument of type 'unsigned int', but
argument X has type 'long unsigned int'"

Signed-off-by: Wolfgang Denk <wd@denx.de>