package/refpolicy: move patches to subdirectory
refpolicy patches are for upstream version but when using a custom version
from git they may fail to apply.
Fixes:
https://gitlab.com/buildroot.org/buildroot/-/jobs/1734417630
Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>