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/hack-5.10/780-usb-net-MeigLink_modem_support.patch

@@ -1,3 +1,17 @@
+From: Daniel Golle <daniel@makrotopia.org>
+Subject: wwan: Add MeigLink SLM750 modem support
+
+Add patch found in Teltonika RUT9_R_00.07.01.4 GPL SDK download[1]
+adding USB IDs of the MeigLink SLM750 to the relevant kernel drivers.
+Newer versions of Teltonika's 2G/3G/4G RUT9XX WWAN router series come
+with this kind of modem.
+
+[1]: https://wiki.teltonika-networks.com/view/GPL
+Submitted-by: Daniel Golle <daniel@makrotopia.org>
+---
+ drivers/net/usb/qmi_wwan.c                    | 8 ++++++
+ 1 file changed, 8 insertions(+)
+
 --- a/drivers/net/usb/qmi_wwan.c
 +++ b/drivers/net/usb/qmi_wwan.c
 @@ -1024,6 +1024,7 @@ static const struct usb_device_id produc