meson: fix suite of alignment check tests

Follow-up for 97318131fd06a5bc35454da81dcbbc84f16d9940.

By default, suite of each built test is determined by the directory of
the source file. Hence, before the mentioned commit, all tests in
src/boot/efi/ are in the 'efi' suite. The commit changed the directory
tree, but forgot to update the name of the test suite.

src/boot/meson.build

@@ -451,7 +451,7 @@ foreach efi_elf_binary : efi_elf_binaries
         test('check-alignment-@0@'.format(name),
              check_efi_alignment_py,
              args : exe.full_path(),
-             suite : 'efi')
+             suite : 'boot')
 endforeach
 
 alias_target('systemd-boot', boot_targets)