crda: removal from kernel 4.15 and onwards.

crda: removal from kernel 4.15 and onwards.

- From kernel 4.15 and onwards the function of what crda does is built into the kernel.
- Tested the removal of crda with kernel 4.14.232 and kernel 5.10.45
   Country code set by "iw reg set NL" was recognised with kernel 5.10.45 and set at
   the global value of 00 with kernel 4.14.232 confirming the kernel built in option is
   working without the prescence of crda

Tested-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>