kbuild: use simpler section mismatch warnings in modpost

The typical layout is now:
WARNING: vmlinux.o(.text+0x372ec): Section mismatch: reference to .devinit.text:pci_scan_one_pbm in 'psycho_scan_bus'

This is first step towards more readable warnings.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>