dt-bindings: PCI: brcm,stb-pcie: Change brcmstb maintainer and cleanup

dt-bindings: PCI: brcm,stb-pcie: Change brcmstb maintainer and cleanup

Change maintainer: Nicolas has not been active for a while. It also
makes sense for a Broadcom employee to be the maintainer as many of the
details are privy to Broadcom.

Also, alphabetize the compatible strings.

Link: https://lore.kernel.org/linux-pci/20240815225731.40276-2-james.quinlan@broadcom.com
Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
[kwilczynski: commit log]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>