drivers: ieee802154: cc13/26xx_subg: R-to-P link workaround

A known issue exists that does not allow a CC13/26x2R device to
establish a link to a CC13/26x2P device unless the capacitor array is
tuned to a non-default value in the P device.

See SimpleLink(TM) cc13xx_cc26xx SDK 6.20+ Release Notes, Known Issues.

Signed-off-by: Florian Grandel <fgrandel@code-for-humans.de>