[nrf51822][gcc_arm]: fix makefile templates and nrf_svc.h's 'impossible constraint in asm' error

Update softdevice path in makefile. The file structue of online compiler projects is different with projects exported by project.py. this is for online compiler.

The offset param of srec_cat should not be used with hex file in this case, as hex file contains address info.

I tested '-Os' option again. It's OK now. It may be a problem of mine. I don't know why : (
To be consistent with the length of uvision's hex file