phy: marvell: a3700-comphy: Fix hardcoded array size

Replace hardcoded 'gbe_phy_init' array size by explicit one.

Fixes: 93433708

 ("phy: marvell: phy-mvebu-a3700-comphy: Add native kernel implementation")
Signed-off-by: Mikhail Kobuk <m.kobuk@ispras.ru>
Link: https://lore.kernel.org/r/20240321164734.49273-2-m.kobuk@ispras.ru
Signed-off-by: Vinod Koul <vkoul@kernel.org>