generic: Convert incorrect generic/5.10 patches

OpenWRT's developer guide prefers having actual patches so they an be
sent upstream more easily.

However, in this case, Adding proper fields also allows for `git am` to
properly function. Some of these patches are quite old, and lack much
traceable history.

This commit tries to rectify that, by digging in the history to find
where and how it was first added.

It is by no means perfect and also shows some patches that should have
been long gone.

Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>

target/linux/generic/pending-5.10/483-mtd-spi-nor-add-gd25q512.patch

@@ -1,3 +1,12 @@
+From: Roman Yeryomin <roman@advem.lv>
+Subject: mtd/spi-nor/gigadevice: Add gd25q512 SPI NOR flash
+
+Submitted-by: Roman Yeryomin <roman@advem.lv>
+Submitted-by: John Crispin <john@phrozen.org>
+---
+ drivers/mtd/spi-nor/gigadevice.c              |    3 +++
+ 1 files changed, 3 insertions(+)
+
 --- a/drivers/mtd/spi-nor/gigadevice.c
 +++ b/drivers/mtd/spi-nor/gigadevice.c
 @@ -53,6 +53,9 @@ static const struct flash_info gigadevic