fix: rename imx8m bare uboot hook so binman pkg_resources patch can run

`imx8m.conf` defined a bare `pre_config_uboot_target()`. The framework
treats a bare hook as the full implementation and drops any
`pre_config_uboot_target__<purpose>` companions, so #9407's
auto-enabled `uboot-binman-fix-pkg-resources` extension was never
firing on i.MX 8M boards — `tools/binman/control.py`'s
`import pkg_resources` stayed unpatched, and `make flash.bin` died
with `ModuleNotFoundError` on Python 3.12 / setuptools >= 82.

Rename to `pre_config_uboot_target__imx8m_firmware()`. Body unchanged.
Both hooks now register and run; order between them doesn't matter
(NXP firmware fetch vs. Python source rewrite are independent).

Repro: armbian/os run 25262303737, job uboot-mba8mpxl-ras314-current.

Author: igorpecovnik

config/sources/families/imx8m.conf

@@ -28,8 +28,11 @@ case $BOARD in
 		;;
 esac
 
-# bootloader releated
-pre_config_uboot_target() {
+# bootloader related.
+# Use `<hook>__<purpose>` so the framework registers this alongside
+# other extensions' hooks at the same stage; a bare
+# `pre_config_uboot_target()` would suppress every other registration.
+pre_config_uboot_target__imx8m_firmware() {
 	# get the firmware
 	rm -rf ${IMX_FIRMWARE}*
 	curl -fL "https://www.nxp.com/lgfiles/NMG/MAD/YOCTO/${IMX_FIRMWARE}.bin" -o "${IMX_FIRMWARE}.bin" || {