hwdb: add hardware rfkill key for Dell Latitude E6* models (#27462)

hwdb: add hardware rfkill key for Dell Latitude E6* models (#27462)

Hello

This pull req is adapting pull req #5772 (which fixed issue #5047), for the very similar computer Dell Latitude E6420 which has the same problem with the hardware switch to toggle wifi (aka rfkill). The symptom is the following repeated msgs in dmesg

[  309.010284] atkbd serio0: Use 'setkeycodes e008 <keycode>' to make it known.
[  309.016020] atkbd serio0: Unknown key pressed (translated set 2, code 0x88 on isa0060/serio0).

Adding this line to include E6 models causes these messages to stop showing in dmesg

Thank you