net: phy: broadcom: extract all registers to brcmphy.h

Commit 439d39a9

 ("net: phy: broadcom:
extract register definitions") added a bunch of registers to brcmphy.h
but left some to broadcom.c, move all of them to the header file since
the BCM54xx and BCM7xxx PHY drivers do share all of these registers.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>