net: phy: realtek: fix rtl8221b-vm-cg name

When splitting the RTL8221B-VM-CG into C22 and C45 variants, the name was
accidentally changed to RTL8221B-VN-CG. This patch brings back the previous
part number.

Fixes: ad5ce743 ("net: phy: realtek: Add driver instances for rtl8221b via Clause 45")
Signed-off-by: Aleksander Jan Bajkowski <olek2@wp.pl>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20251016192325.2306757-1-olek2@wp.pl


Signed-off-by: Jakub Kicinski <kuba@kernel.org>