generic: 6.1: renumber MediaTek SGMII PCS patch

Renumber MediaTek SGMII PCS patch to make space for upcoming at803x
backport patches.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

diff --git a/target/linux/generic/backport-6.1/707-v6.3-net-pcs-add-driver-for-MediaTek-SGMII-PCS.patch b/target/linux/generic/backport-6.1/723-v6.3-net-pcs-add-driver-for-MediaTek-SGMII-PCS.patch
similarity index 100%
rename from target/linux/generic/backport-6.1/707-v6.3-net-pcs-add-driver-for-MediaTek-SGMII-PCS.patch
rename to target/linux/generic/backport-6.1/723-v6.3-net-pcs-add-driver-for-MediaTek-SGMII-PCS.patch