net/fsl: xgmac_mdio: use correct format characters

net/fsl: xgmac_mdio: use correct format characters

When compiling with -Wformat, clang emits the following warning:

drivers/net/ethernet/freescale/xgmac_mdio.c:243:22: warning: format
specifies type 'unsigned char' but the argument has type 'int'
[-Wformat]
                        phy_id, dev_addr, regnum);
                                          ^~~~~~
./include/linux/dev_printk.h:163:47: note: expanded from macro 'dev_dbg'
                dev_printk(KERN_DEBUG, dev, dev_fmt(fmt), ##__VA_ARGS__); \
                                                    ~~~     ^~~~~~~~~~~
./include/linux/dev_printk.h:129:34: note: expanded from macro 'dev_printk'
                _dev_printk(level, dev, fmt, ##__VA_ARGS__);            \
                                        ~~~    ^~~~~~~~~~~

The types of these arguments are unconditionally defined, so this patch
updates the format character to the correct ones for ints and unsigned
ints.

Link: https://github.com/ClangBuiltLinux/linux/issues/378
Signed-off-by: Bill Wendling <morbo@google.com>
Link: https://lore.kernel.org/r/20220316213114.2352352-1-morbo@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>