mediatek: 5.15: add missing patch suffix

The 213 patch is missing filename suffix. Fix it.

Fixes: dabcaac ("mediatek: add mt7986 soc support to the target")
Signed-off-by: Chukun Pan <amadeus@jmu.edu.cn>

diff --git a/target/linux/mediatek/patches-5.15/213-spi-mediatek-add-mt7986-spi-support b/target/linux/mediatek/patches-5.15/213-spi-mediatek-add-mt7986-spi-support.patch
similarity index 100%
rename from target/linux/mediatek/patches-5.15/213-spi-mediatek-add-mt7986-spi-support
rename to target/linux/mediatek/patches-5.15/213-spi-mediatek-add-mt7986-spi-support.patch