main/linux-postmarketos-qcom-msm8974: upgrade to 5.14.2

Keernel changelog: nothing new specifically for msm8974. Just routine rebase of our msm8974 patchset on top of newer kernel release.

Some smaller things:

• parts of bam-dmux patchset are now upstream (1 of 6 commits?)
• upstream WWAN subsystem has qcom's rpmsg driver which should work with newer ModemManager OOTB (?) (TODO: test this)
• qcom clk-rcg2 now supports support for duty-cycle, so this commit by Brian Masney is no longer needed (it does not apply anyway). Hopefully @masneyb's clk-vibrator patchset is not broken now because of this replacement

TODO:

• first migrate kconfig, then
• test on lg-hammerhead @JuniorJPDJ / @wonderfulShrineMaidenOfParadise / @tallero ? test vibrator specifically
• test on oneplus-bacon @Kanedias
• test on sony-castor @julianuu
• test on fairphone-fp2 @z3ntu
• test on samsung-klte @minlexx

This includes small cleanups for some 8974-device packages:

• due to kernel changes, msm-modem-rpmsg is no longer needed in deps, replaced by msm-modem
• long overdue change mesa-dri-freedreno => mesa-dri-gallium (mesa has one single megadriver for all)
• lg-hammerhead gained swclock-offset to preserve system time, workaround for qcom's read-only RTC and lost ofono from deps - oFono should be pulled by UI packages that depend on it.
• deps list was sorted and became more readable