elantech: Support for ElanTech touchpad, fw 0x480f0a

Hello. First time posting to a Linux ML, new to drivers in general.

So I got an ASUS PU551LD laptop and quickly found out Linux 3.18.3 wasn't 
detecting the touchpad correctly. After some digging, I figured out that it is 
an ElanTech touchpad which reports firmware version 0x480f0a, then poked 
around in drivers/input/mouse/elantech.c and tried changing 
'elantech_is_signature_valid' to always return true. This made the device work 
properly with all the expected features, and it shows up in dmesg like this:

psmouse serio4: elantech: assuming hardware version 4 (with firmware version 
0x480f0a)
psmouse serio4: elantech: Synaptics capabilities query result 0x40, 0x17, 
0x0c.
input: ETPS/2 Elantech Touchpad as /devices/platform/i8042/serio4/input/input8

Now of course I want to help getting support for this particular model into 
the kernel, but I would feel bad about posting a patch that just adds more 
magic numbers to the function in question. Any suggestions?