sharpyuv: remove minimum image size from sharpyuv library
sharpyuv: remove minimum image size from sharpyuv library

libwebp still has a size threshold of 4 pixels in picture_csp_enc.c
but the sharpyuv library itself can handle any image size.

Change-Id: Ic1c78c8f8fae528395fa46a74f717f47cb13098e

webmproject/libwebp,webmproject/libwebp,webmproject/libwebp,webmproject/libwebp,webmproject/libwebp