realtek: fix zyxel-vers usage for XGS1250-12
Commit daefc646e6d4 ("realtek: fix ZyXEL initramfs image generation")
fixed a shell expansion issue with zyxel-vers usage. Commit 045baca10b15
("realtek: deduplicate GS1900 recipes") took care of this for the
rtl838x and rtl839x subtargets, but the single device officially
supported in rtl930x - the XGS1250-12 - was overlooked. This commit
updates the XGS1250-12 build recipe as well.
Signed-off-by: Stijn Segers <[email protected]>
Stijn Segers