agl-flutter: update layer dependencies

agl-flutter: update layer dependencies

meta-agl-flutter now requires meta-multimeda for libcamera with its
default configuration, make sure that layer gets added when the
agl-flutter feature is used.  This fixes builds without "agl-demo".

Bug-AGL: SPEC-5193

Change-Id: Ic3203446c66a6008a0a02ff15c0b85f1cedff546
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/30121
ci-image-build: Jenkins Job builder account
Tested-by: Jenkins Job builder account
ci-image-boot-test: Jenkins Job builder account
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>