CI: remove msm-firmware-loader from shellcheck (MR 3260)

msm-firmware-loader is in its own repo now.

.ci/shellcheck.sh

@@ -28,7 +28,6 @@ sh_files="
 	./main/swclock-offset/swclock-offset-shutdown.sh
 	./main/ttyescape/*.post-install
 	./main/unl0kr/unlock.sh
-	./main/msm-firmware-loader/*.sh
 	./main/msm-firmware-loader/*.post-install
 
 	$(find . -path './main/postmarketos-ui-*/*.sh')