linux (Generic): update to linux-5.5

[MilhouseVH]

Usual nonsense with Nvidia drivers which no longer build due to torvalds/linux@4e98f87 and torvalds/linux@62afb4a (and possibly others). Disabled until updated drivers become available.

5.5-rc3:

• Both nvidia drivers enabled with 5.5-rc3 (xf86-video-nvidia-legacy requires xf86-video-nvidia-legacy: update to xf86-video-nvidia-legacy-340.108 #4075).

Test build posts

Kernel	RPi/RPi2	Generic	Announce
5.5-rc1		#1209x	Link
5.5-rc2		#1217x	Link
5.5-rc3		#1223x	Link
5.5-rc4		#1230x	Link
5.5-rc5	#0106x	#0106x	Link
5.5-rc6		#0113x	Link
5.5-rc7	#0120x	#0120x	Link

[MilhouseVH]

Added xf86-video-nvidia-440.59 as that allows us to drop the kernel-5.5 patch fix: forum, download.

Bumped kernel-firmware to include AMD Renoir and Raven2 19.50 firmware.

[HiassofT]

can you split off the RPi changes from this PR?

As discussed on slack it'd be best to track 5.4 for RPi in LE master for a while so we can move forward with v4l2 and kms (first on RPi4, then RPi+RPi2).

quote from popcornmix:

5.4 is the kernel we are developing against (including John and Maxime for v4l2/kms). We will aim to support 5.5 as well, but it will be less well tested. As long as you can easily switch between 5.4 and 5.5 to confirm if there are regressions on 5.5 we can probably cherry-pick or fix it up, but it might be worth doing initial testing on 5.4 as it's more likely to be working with new features.

[MilhouseVH]

I'll revert the 5.5 changes back to 5.14.y for RPi. I don't agree with this change, because following an LTS kernel in LE master has few long term benefits from a testing POV but assuming this is a short-term exception and it helps speed RPi4 development then I'll do it, but eventually we need to get RPi back on to mainline (and stay there).