[PATCH net-next v3] netmem: replace __netmem_clear_lsb() with netmem_to_nmdesc()

[Byungchul Park]

Changes from RFC v2:
	1. Add a Reviewed-by tag (Thanks to Mina)
	2. Rebase on main branch as of Sep 22

Changes from RFC:
	1. Optimize the implementation of netmem_to_nmdesc to use less
	   instructions (feedbacked by Pavel)

--->8---