kernel: bump 5.4 to 5.4.87

kernel: bump 5.4 to 5.4.87

All modification by update_kernel.sh.

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

No dmesg regressions, everything functional

Compile-tested [*]: ath79/{generic,tiny}, ipq40xx, octeon,
                    ramips/mt7621, realtek, x86/64.
Run-tested [*]:     ramips/mt7621 (DIR-878 A1, R6800, RT-AC57U),
                    octeon (EdgeRouter Lite).

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