hwdef: remove save_some_flash.inc

[peterbarker]

all but one board was getting all of these includes from minimize_fpv_osd, and the remaining board had most lines foming from minimize_features.inc.

This file has served its purpose, its role now taken on by minimize_fpv_osd.inc

[peterbarker]

I've run this through size_compare_branches.py and the only builds changed are:

pbarker@threads:~/rc/ardupilot$ ~/rc/ardupilot/Tools/scripts/filter_size_compare_branches_csv.py /tmp/some.csv  --hide-bin 
------------------------  -----  ------  ----  -----  -----  ---
Board                     blimp  copter  heli  plane  rover  sub
SITL_arm_linux_gnueabihf  0      0       0     0      0      0
SITL_x86_64_linux_gnu     0      0       0     0      0      0
------------------------  -----  ------  ----  -----  -----  ---
pbarker@threads:~/rc/ardupilot$ 

... we really should try to make those ones binary-identical for any change which should produce the same binaries at some stage...