soc: nordic: nrf54h20: add support for nRF54H20 EngB

nRF54H20 EngB is a re-label to the existing hardware revision for the
nRF54H20. nRF54H20 (whithout EngX) is becoming the final revision of the
SoC.

Signed-off-by: Gerard Marull-Paretas <gerard@teslabs.com>