fix(drivers/marvell/comphy-3700): fix Generation Setting registers names

According to Functional Specification, the common PHY register at offset
0x3f is actually Generation 3 Setting 2, while the register at offset
0x112 is Generation 2 Setting 3.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Change-Id: I4626672cbee2d08da1da7839a3cf3f90e78fa101
2 files changed