kernel: bump 5.4 to 5.4.93

kernel: bump 5.4 to 5.4.93

All modification made by update_kernel.sh in a fresh clone without
existing toolchains.

Build system:       x86_64
Build-tested:       ipq806x/R7800, bcm27xx/bcm2711
Run-tested:         ipq806x/R7800
Compile-tested [*]: ath79/{tiny,generic}, ipq40xx, octeon,
                    ramips/mt7621, realtek, x86/64
Run-tested [*]:     ath79/generic, ipq40xx, octeon, ramips/mt7621

No dmesg regressions, everything functional

Signed-off-by: John Audia <graysky@archlinux.us>
Tested-by: Stijn Segers <foss@volatilesystems.org> [*]