m68k: Fix asm register constraints for atomic ops

Depending on register assignment by the compiler:

    {standard input}:3084: Error: operands mismatch -- statement `andl %a1,%d1' ignored
    {standard input}:3145: Error: operands mismatch -- statement `orl %a1,%d1' ignored
    {standard input}:3195: Error: operands mismatch -- statement `eorl %a1,%d1' ignored

Indeed, the first operand must not be an address register.  However, it
can be an immediate value.  Fix this by adjusting the register
constraint from "g" (general purpose register) to "di" (data register or
immediate).

Fixes: e39d88ea ("locking/atomic, arch/m68k: Implement atomic_fetch_{add,sub,and,or,xor}()")
Fixes: d839bae4 ("locking,arch,m68k: Fold atomic_ops")
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20210809112903.3898660-1-geert@linux-m68k.org