phy: marvell: core: Cosmetic fixes

Move the reg_set* functions into comphy.h as static inline functions.
Change return type of get_*_string to const char *.

Signed-off-by: Marek Behun <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Stefan Roese <sr@denx.de>
2 files changed