libcamera: MappedFrameBuffer: Use typed Flags<MapModes>

Remove the need for callers to reference PROT_READ/PROT_WRITE directly
from <sys/mman.h> by instead exposing the Read/Write mapping options as
flags from the MappedFrameBuffer class itself.

While here, introduce the <stdint.h> header which is required for the
uint8_t as part of the Plane.

Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/ipa/raspberrypi/raspberrypi.cpp

@@ -411,7 +411,8 @@ void IPARPi::mapBuffers(const std::vector<IPABuffer> &buffers)
 {
 	for (const IPABuffer &buffer : buffers) {
 		const FrameBuffer fb(buffer.planes);
-		buffers_.emplace(buffer.id, MappedFrameBuffer(&fb, PROT_READ | PROT_WRITE));
+		buffers_.emplace(buffer.id,
+				 MappedFrameBuffer(&fb, MappedFrameBuffer::MapFlag::ReadWrite));
 	}
 }