dt-bindings: bcm4329-fmac: add optional brcm,ccode-map-trivial

The bindings already offer a brcm,ccode-map property to describe the
mapping between the kernel's ISO3166 alpha 2 country code string and the
firmware's country code string and revision number. This is a
board-specific property and determined by the CLM blob firmware provided
by the hardware vendor.

However, in some cases the firmware will also use ISO3166 country codes
internally, and the revision will always be zero. This implies a trivial
mapping: cc -> { cc, 0 }.

For such cases, add an optional property brcm,ccode-map-trivial which
obviates the need to describe every trivial country code mapping in the
device tree with the existing brcm,ccode-map property. The new property
is subordinate to the more explicit brcm,ccode-map property.

Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220711123005.3055300-2-alvin@pqrs.dk