asm-generic: compat: fix compat_arg_u64() and compat_arg_u64_dual()

The macros are defined backwards.

This affects the following compat syscalls:
 - compat_sys_truncate64()
 - compat_sys_ftruncate64()
 - compat_sys_fallocate()
 - compat_sys_sync_file_range()
 - compat_sys_fadvise64_64()
 - compat_sys_readahead()
 - compat_sys_pread64()
 - compat_sys_pwrite64()

Fixes: 43d5de2b

 ("asm-generic: compat: Support BE for long long args in 32-bit ABIs")
Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
[mpe: Add list of affected syscalls]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/871qqoyvni.fsf_-_@igel.home