realtek: Convert incorrect v5.10 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/realtek/patches-5.10/310-add-i2c-rtl9300-support.patch

@@ -1,3 +1,20 @@
+From 63a0a4d85bc900464c5b046b13808a582345f8c8 Mon Sep 17 00:00:00 2001
+From: Birger Koblitz <git@birger-koblitz.de>
+Date: Sat, 11 Dec 2021 20:14:47 +0100
+Subject: [PATCH] realtek: Add support for RTL9300/RTL9310 I2C controller
+
+This adds support for the RTL9300 and RTL9310 I2C controller.
+The controller implements the SMBus protocol for SMBus transfers
+over an I2C bus. The driver supports selecting one of the 2 possible
+SCL pins and any of the 8 possible SDA pins. Bus speeds of
+100kHz (standard speed) and 400kHz (high speed I2C) are supported.
+
+Submitted-by: Birger Koblitz <git@birger-koblitz.de>
+---
+ drivers/i2c/busses/Kconfig                    | 10 +++++++++
+ drivers/i2c/busses/Makefile                   |  1 +
+ 2 files changed, 11 insertions(+)
+
 --- a/drivers/i2c/busses/Kconfig
 +++ b/drivers/i2c/busses/Kconfig
 @@ -954,6 +954,16 @@ config I2C_RK3X