kernel: bump 5.4 to 5.4.75

Manually rebased patches:
  bcm27xx:
    patches-5.4/950-0267-xhci-add-quirk-for-host-controllers-that-don-t-updat.patch
  bcm53xx:
    patches-5.4/180-usb-xhci-add-support-for-performing-fake-doorbell.patch
  layerscape:
    patches-5.4/802-can-0025-can-flexcan-add-LPSR-mode-support-for-i.MX7D.patch
    patches-5.4/808-i2c-0002-MLK-10893-i2c-imx-add-irqf_no_suspend.patch
    patches-5.4/820-usb-0016-MLK-16735-usb-host-add-XHCI_CDNS_HOST-flag.patch

Removed since could be reverse-applied by quilt:
  mediatek:
    patches-5.4/0700-arm-dts-mt7623-add-missing-pause-for-switchport.patch

All modifications made by update_kernel.sh

Build system: x86_64
Build-tested: ipq806x/R7800, ath79/generic, bcm27xx/bcm2711, x86_64
Run-tested: ipq806x/R7800, x86_64

No dmesg regressions, everything functional

Signed-off-by: John Audia <graysky@archlinux.us>
Tested-by: Curtis Deptuck <curtdept@me.com> [x86_64]

Rebase of 802-can-0025-can-flexcan-add-LPSR-mode-support-for-i.MX7D.patch
Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Signed-off-by: Kevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk>

target/linux/generic/pending-5.4/920-mangle_bootargs.patch

@@ -13,7 +13,7 @@ Signed-off-by: Imre Kaloz <kaloz@openwrt.org>
 
 --- a/init/Kconfig
 +++ b/init/Kconfig
-@@ -1662,6 +1662,15 @@ config EMBEDDED
+@@ -1663,6 +1663,15 @@ config EMBEDDED
  	  an embedded system so certain expert options are available
  	  for configuration.