x86/mm: Replace nodes_weight() with nodes_empty() where appropriate

Various mm code calls nodes_weight() to check if any bit of a given
nodemask is set.

This can be done more efficiently with nodes_empty() because nodes_empty()
stops traversing the nodemask as soon as it finds first set bit, while
nodes_weight() counts all bits unconditionally.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220210224933.379149-26-yury.norov@gmail.com