rename util/spkmodem-recv to spkmodem-decode

it's no longer resembling the original util at all,
so a rename seems indicated. yes.

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/spkmodem_decode/Makefile

@@ -0,0 +1,30 @@
+# SPDX-License-Identifier: MIT
+# SPDX-FileCopyrightText: 2022,2026 Leah Rowe <leah@libreboot.org>
+# SPDX-FileCopyrightText: 2023 Riku Viitanen <riku.viitanen@protonmail.com>
+
+CC?=cc
+CFLAGS?=-Os -Wall -Wextra -Werror -pedantic -std=c90
+DESTDIR?=
+PREFIX?=/usr/local
+INSTALL?=install
+
+PROG=spkmodem-decode
+
+all: $(PROG)
+
+$(PROG): spkmodem-decode.c
+	$(CC) $(CFLAGS) spkmodem-decode.c -o $(PROG)
+
+install: $(PROG)
+	mkdir -p $(DESTDIR)$(PREFIX)/bin/
+	install -c $(PROG) $(DESTDIR)$(PREFIX)/bin/
+
+uninstall:
+	rm -f $(DESTDIR)$(PREFIX)/bin/$(PROG)
+
+clean:
+	rm -f $(PROG)
+
+distclean: clean
+
+.PHONY: all install uninstall clean distclean