libkmod-module: Remove key+value vermagic from .modinfo section

libkmod-module: Remove key+value vermagic from .modinfo section

When told to force load a module, we were removing only the value of
vermagic instead of the complete entry.

Philippe De Swert (philippe.deswert@jollamobile.com) sent a patch that
was additionally mangling also the last two chars of the key
("vermagic="). Instead of creating an invalid entry in .modinfo section
like this, this patch removes the complete entry, key + value, by
zeroing the entire string.

Much thanks to Philippe who found the issue and pointed to the fix.