Moving kernel to Linux 5.3

[Joel Stanley]

With Linux v5.3 tagged today I've created an openbmc tree based on this release.

We have 120 patches in dev-5.3. Of these, 56 are backported from
upstream, leaving 64 out of tree patches. These out of tree patches
include long standing mtd and fan controller changes, the aging PECI
patch set, and a few Nuvoton drivers.

Most of the patches from dev-5.2 are carried over. One exception is
the aspeed i2c experiments, which I have asked Jae to post upstream
for review before we include them again.

This tree contains support for the ast2600 that was merged in 5.4.

I have tested on ast2400 (palmetto), ast2500 (romulus), ast2600
(palmetto), both hardware and qemu (aspeed-4.2 branch). Further
testing and a +1 of this review would be appreciated:

 https://gerrit.openbmc-project.xyz/c/openbmc/meta-aspeed/+/25213

Cheers,

Joel