realme-rmx1851: Removed modules-initfs, not currently needed

device/testing/device-realme-rmx1851/modules-initfs

-# This file can contain a list of modules to be included in the initramfs,
-# so that they are available in early boot stages. It should have one
-# module name per line. If there are multiple kernel variants with different
-# requirements for modules into the initramfs, one modules-initfs.$variant
-# file should be created for each of them.