liveupdate: luo_core: fix redundant bound check in luo_ioctl()

The kernel test robot reported a Smatch warning:
kernel/liveupdate/luo_core.c:402 luo_ioctl() warn: unsigned 'nr' is
never less than zero.

This occurs because 'nr' is unsigned and LIVEUPDATE_CMD_BASE is currently
defined as 0, making the check (nr < LIVEUPDATE_CMD_BASE) always false.

Remove the explicit lower bound check. The logic remains correct because
'nr' is unsigned; if nr is less than LIVEUPDATE_CMD_BASE, the expression
(nr - LIVEUPDATE_CMD_BASE) will wrap around to a large positive value.
This will inevitably be larger than ARRAY_SIZE(luo_ioctl_ops) and be
caught by the upper bound check.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Pasha Tatashin <[e-mail]>
Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Reviewed-by: Mike Rapoport (Microsoft) <[e-mail]>
Cc: David Matlack <[e-mail]>
Cc: Pratyush Yadav <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

kernel/liveupdate/luo_core.c

···
 	int err;
 
 	nr = _IOC_NR(cmd);
-	if (nr < LIVEUPDATE_CMD_BASE ||
-	    (nr - LIVEUPDATE_CMD_BASE) >= ARRAY_SIZE(luo_ioctl_ops)) {
+	if (nr - LIVEUPDATE_CMD_BASE >= ARRAY_SIZE(luo_ioctl_ops))
 		return -EINVAL;
-	}
 
 	ucmd.ubuffer = (void __user *)arg;
 	err = get_user(ucmd.user_size, (u32 __user *)ucmd.ubuffer);