rfkill: uapi: fix RFKILL_IOCTL_MAX_SIZE ioctl request definition

The definition of RFKILL_IOCTL_MAX_SIZE introduced by commit
54f586a9 ("rfkill: make new event layout opt-in") is unusable
since it is based on RFKILL_IOC_EXT_SIZE which has not been defined.
Fix that by replacing the undefined constant with the constant which
is intended to be used in this definition.

Fixes: 54f586a9 ("rfkill: make new event layout opt-in")
Cc: stable@vger.kernel.org # 5.11+
Signed-off-by: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Link: https://lore.kernel.org/r/20220506172454.120319-1-glebfm@altlinux.org


[add commit message provided later by Dmitry]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>