net: phy: broadcom: add support for BCM54210E

It's Broadcom PHY simply described as single-port
RGMII 10/100/1000BASE-T PHY. It requires disabling
delay skew and GTXCLK bits.

BCM54210E support ported from Linux kernel commit
0fc9ae1076697 ("net: phy: broadcom: add support for BCM54210E")
AUX/SHD/bcm54xx_config_clock_delay update ported from Linux 6.5-rc4 commit
28e219aea0b9e ("net: phy: broadcom: drop brcm_phy_setbits() and use phy_set_bits() instead")

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Rafał Miłecki <rafal@milecki.pl>