material.cpp speedup

When checking for very few or no pawns for scale factor, if there are no pawns don't check for one pawn.
Bench results below:

Base	Speed
4097	4033
4094	4032
4094	4032
4110	4048
4094	4036
4095	4032
4109	4016
4095	4016
4094	4031
	
Averages	
4098	4031
	
1.7% Speed up	

No functional change