LinuxKPI: Constify src parameter of bitmap_copy

in bitmap_from_arr32() to fix build on 32 bit archs.

Sponsored by: Serenity Cyber Security, LLC
Fixes: 5ae2e6f913fa ("LinuxKPI: Add bitmap_intersects(), bitmap_from_arr32()")
MFC after: 1 week

(cherry picked from commit dbca442414191a43f334435b7910b63cb2777d53)