[armhf] Rename kconfig files to default per-arch and per-flavour filenames

config.armmp is used by both flavours and there's unlikely to be a
reason to add any non-multiplatform flavour.  Rename it so that it's
the per-architecture config.

config.lpae is then the only per-flavour config file for armmp-lpae,
so rename it to the default filename for that flavour.

debian/config/armhf/defines

@@ -10,7 +10,6 @@ vdso: true
 
 [image]
 suggests: fdutils
-configs:
 install-stem: vmlinuz
 
 [relations]
@@ -27,9 +26,3 @@ hardware: ARMv7 multiplatform compatible SoCs supporting LPAE
 hardware-long: ARMv7 multiplatform kernel supporting LPAE. See
   https://wiki.debian.org/DebianKernel/ARMMP for details of supported
   platforms.
-
-[armmp-lpae_image]
-configs:
- armhf/config.armmp
- armhf/config.lpae
-