p54: regulatory domain hints

This patch adds a sub-routine that parses the default country eeprom entry
and forwards the obtained Alpha2 identifier to the regulatory sub-system.

Note: I dropped the p54 specific regdomain<->alpha2 conversion code for now.
But it will be added as soon as there's the common library function is ready.

Signed-off-by: Christian Lamparter <chunkeey@web.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>