Enable the flutter-pi vulkan option if a suitable driver is enabled.
Currently, only Mesa provides Vulkan drivers. As such, gating the
feature behind the BR2_PACKAGE_MESA3D_VULKAN_DRIVER option is
reasonable at the moment and is done by three other packages already:
flutter-engine, ivi-home screen, and wlroots.
Furthermore, a dependency on BR2_PACKAGE_VULKAN_LOADER is needed as the
vulkan-loader package provides the vulkan.pc file, which the configure step
relies upon.
Signed-off-by: Adam Duskett <adam.duskett@amarulasolutions.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>