kernel: 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
Signed-off-by: Daniel Golle <daniel@makrotopia.org>

target/linux/generic/hack-5.10/780-usb-net-MeigLink_modem_support.patch

@@ -0,0 +1,33 @@
+--- 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
+ 	{QMI_MATCH_FF_FF_FF(0x2c7c, 0x0512)},	/* Quectel EG12/EM12 */
+ 	{QMI_MATCH_FF_FF_FF(0x2c7c, 0x0620)},	/* Quectel EM160R-GL */
+ 	{QMI_MATCH_FF_FF_FF(0x2c7c, 0x0800)},	/* Quectel RM500Q-GL */
++	{QMI_MATCH_FF_FF_FF(0x05c6, 0xf601)},   /* MeigLink SLM750 */
+
+ 	/* 3. Combined interface devices matching on interface number */
+ 	{QMI_FIXED_INTF(0x0408, 0xea42, 4)},	/* Yota / Megafon M100-1 */
+--- a/drivers/usb/serial/option.c
++++ b/drivers/usb/serial/option.c
+@@ -243,6 +243,8 @@ static void option_instat_callback(struc
+ #define UBLOX_PRODUCT_R6XX			0x90fa
+ /* These Yuga products use Qualcomm's vendor ID */
+ #define YUGA_PRODUCT_CLM920_NC5			0x9625
++/* These MeigLink products use Qualcomm's vendor ID */
++#define MEIGLINK_PRODUCT_SLM750			0xf601
+
+ #define QUECTEL_VENDOR_ID			0x2c7c
+ /* These Quectel products use Quectel's vendor ID */
+@@ -1127,6 +1129,11 @@ static const struct usb_device_id option
+ 	{ USB_DEVICE_AND_INTERFACE_INFO(QUECTEL_VENDOR_ID, QUECTEL_PRODUCT_EG95, 0xff, 0, 0) },
+ 	{ USB_DEVICE(QUECTEL_VENDOR_ID, QUECTEL_PRODUCT_BG96),
+ 	  .driver_info = RSVD(4) },
++	/* Meiglink products using Qualcomm vendor ID */
++	// Works OK. In case of some issues check macros that are used by Quectel Products
++	{ USB_DEVICE_AND_INTERFACE_INFO(QUALCOMM_VENDOR_ID, MEIGLINK_PRODUCT_SLM750, 0xff, 0xff, 0xff),
++	  .driver_info = NUMEP2 },
++	{ USB_DEVICE_AND_INTERFACE_INFO(QUALCOMM_VENDOR_ID, MEIGLINK_PRODUCT_SLM750, 0xff, 0, 0) },
+ 	{ USB_DEVICE_AND_INTERFACE_INFO(QUECTEL_VENDOR_ID, QUECTEL_PRODUCT_EP06, 0xff, 0xff, 0xff),
+ 	  .driver_info = RSVD(1) | RSVD(2) | RSVD(3) | RSVD(4) | NUMEP2 },
+ 	{ USB_DEVICE_AND_INTERFACE_INFO(QUECTEL_VENDOR_ID, QUECTEL_PRODUCT_EP06, 0xff, 0, 0) },