ramips: move spi-nor-add-gd25q512 patch to generic

A SPI NOR flash should not be target-specific, so move it to generic in
case another platform needs to use it.

Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>

diff --git a/target/linux/ramips/patches-5.10/420-spi-nor-add-gd25q512.patch b/target/linux/generic/pending-5.10/483-mtd-spi-nor-add-gd25q512.patch
similarity index 100%
rename from target/linux/ramips/patches-5.10/420-spi-nor-add-gd25q512.patch
rename to target/linux/generic/pending-5.10/483-mtd-spi-nor-add-gd25q512.patch