1. Combine code for IAR and GCC in file mmu.c and cpuport.c
2. Remove remap code in start_xxx.S. User should config MMU to map vector table to visual address 0x0

1. [bsp][sam9260] Fix the bug that auto reset after boot 20s. Disable watchdog in rt_lovel_level_init function.
2. [bsp][sam9260] Modify SCONS scripts to support IAR tool chain.
3. [bsp][sam9260] Move link strips in to folder link_scripts.
4. [libcpu][arm926] Add copy right to source file and format code.