MAINTAINERS: Add myself as maintainer for apple-gfx, reviewer for HVF

MAINTAINERS: Add myself as maintainer for apple-gfx, reviewer for HVF

I'm happy to take responsibility for the macOS PV graphics code. As
HVF patches don't seem to get much attention at the moment, I'm also
adding myself as designated reviewer for HVF and x86 HVF to try and
improve that.

Signed-off-by: Phil Dennis-Jordan <phil@philjordan.eu>
Reviewed-by: Roman Bolshakov <rbolshakov@ddn.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20241223221645.29911-6-phil@philjordan.eu>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>