bcm47xx: fix bgmac MTU patch filename

Fixes: 4970dd027bce ("bcm47xx: revert bgmac back to the old limited max frame size")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

diff --git a/target/linux/bcm47xx/patches-5.15/701-net-bgmac-connect-to-PHY-even-if-it-is-BGMAC_PHY_NOR.patch b/target/linux/bcm47xx/patches-5.15/701-bgmac-reduce-max-frame-size-to-support-just-MTU-1500.patch
similarity index 100%
rename from target/linux/bcm47xx/patches-5.15/701-net-bgmac-connect-to-PHY-even-if-it-is-BGMAC_PHY_NOR.patch
rename to target/linux/bcm47xx/patches-5.15/701-bgmac-reduce-max-frame-size-to-support-just-MTU-1500.patch