Fix compiler warnings for PPC systems. Update CHANGELOG.

CHANGELOG

board/freescale/mpc8544ds/mpc8544ds.c

board/tqm5200/tqm5200.c

common/usb_storage.c

cpu/mpc86xx/spd_sdram.c

cpu/mpc86xx/speed.c

drivers/ati_radeon_fb.c

drivers/bios_emulator/besys.c

drivers/bios_emulator/biosemu.c

drivers/tsec.c

drivers/tsi108_i2c.c

drivers/tsi108_pci.c