meta-agl-bsp: update raspberrypi5 template

Update the raspberrypi5 template .inc file to drop the extra
U-Boot enabling configuration, as those tweaks are now available
in the new scarthgap branch in meta-raspberrypi.

Bug-AGL: SPEC-5164

Change-Id: Ib65d2b722ea6274b32061262d780c80436fac036
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/29974
Tested-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>