Make menu description of bit depth consistent between mlv_lite and mlv_rec

[reticulatedpines]

These two modules have sub-menu choices that currently use "14-bit" in one, and "14bpp" in the other. Make consistent.

Preferred format: "14 bit". Probably easiest to read? Open to discussion.

Haven't tested it yet, but I think mlv_lite is bringing in the menu from mlv_rec, via mlv.o.