Update to the latest kernel and drop two patches related to Omnia LEDs
as they were merged upstream.

Kernel 5.15 updated to version 5.15.135 and 5.10 updated to 5.10.198.

Update hashes in patch for new versions

Although the hash was changed, the kernel version wasn't so fixing it
now.

Manually rebased:
	backport-5.15/346-v5.18-01-Revert-ata-ahci-mvebu-Make-SATA-PHY-optional-for-Arm.patch
	backport-5.15/603-v5.19-page_pool-Add-recycle-stats-to-page_pool_put_page_bu.patch
	pending-5.15/723-net-mt7531-ensure-all-MACs-are-powered-down-before-r.patch*

Removed upstreamed:
	backport-5.15/705-12-v6.0-net-dsa-mt7530-rework-mt753-01-_setup.patch[2]
	backport-5.15/703-10-v5.16-net-dsa-introduce-helpers-for-iterating-through-port.patch[4]

remove two upstreamed patches and manually rebase one patch

* remove upstreamed 804-0001-net-Remove-WARN_ON_ONCE-sk-sk_forward_alloc-from-sk_.patch
* manually rebase 611-v5.12-net-ethernet-mediatek-support-setting-MTU.patch

Removed patches were included in Linux kernel

Fixes: 5ce2c2ab
("patches/openwrt: Linux kernel 5.15: update to 5.15.86")

this can cause fetch to fail on some systems because the build system
can not detect the checksum type with this trailing space

This was allowed because in OpenWrt 21.02 branch, there is now included
this commit [1].

[1]
https://github.com/openwrt/openwrt/commit/cbce6c6d9519ab86e11c9752910a4c72dd52cb58
("kernel: split kernel version to dedicated files")