meson: ipa: Use files() to locate the mojom files

Use meson's files() to list the mojom files instead of the file names
directly. This is so that we can still access the files from
src/libcamera/ipa/meson.build later for building documentation cpp
files from the mojom files.

While at it, fix some redundant string manipulation in building the
mojom modules.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>

include/libcamera/ipa/meson.build

@@ -81,7 +81,7 @@ foreach file : ipa_mojom_files
     endif
 
     # {pipeline}.mojom-module
-    mojom = custom_target(file.split('.')[0] + '_mojom_module',
+    mojom = custom_target(name + '_mojom_module',
                           input : file,
                           output : file + '-module',
                           depends : ipa_mojom_core,
@@ -143,3 +143,5 @@ foreach file : ipa_mojom_files
 
     libcamera_generated_ipa_headers += [header, serializer, proxy_header]
 endforeach
+
+ipa_mojom_files = files(ipa_mojom_files)