cy8ckit_062_ble: board: moved uart-6 to common dts for m4

Moved uatr6 to common dts for m4

- cm0 uses uart-5 in ver 0.0.0 and uart-5 in ver 1.0.0 (for
using of Arduino headers).

- cm4 by default uses uart-2 (for ver 0.0.0 and ver 1.0.0)

Signed-off-by: Nazar Palamar <nazar.palamar@infineon.com>