dm: sparc: net: Fixup greth compile warnings

greth.c: In function ‘greth_recv’:
greth.c:507:3: warning: format ‘%lx’ expects argument of type ‘long unsigned int’, but argument 2 has type ‘unsigned int’ [-Wformat]
greth.c:507:3: warning: format ‘%lx’ expects argument of type ‘long unsigned int’, but argument 3 has type ‘unsigned int’ [-Wformat]
greth.c:541:6: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
greth.c: In function ‘greth_initialize’:
greth.c:623:2: warning: format ‘%lx’ expects argument of type ‘long unsigned int’, but argument 2 has type ‘struct greth_regs *’ [-Wformat]
greth.c:655:3: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 2 has type ‘struct greth_regs *’ [-Wformat]
greth.c:684:2: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 2 has type ‘struct greth_regs *’ [-Wformat]

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Joe Hershberger <joe.hershberger@gmail.com>
Cc: Daniel Hellstrom <daniel@gaisler.com>
Cc: u-boot-dm@lists.denx.de