Implement SIC_IAR registers

[mheistermann]

Output from ./bfin-softmmu/qemu-system-bfin -gdb tcp::1234 -nographic -monitor none -kernel DR-05_44.211-dxe1.o -d 'in_asm,unimp,nochain,trace:bfin_reg_memory_*' -singlestep

0x0000d0f6:  P1.H = 0xffc0;             /* (-64)        P1=0x0xffc00150(-4193968) */
[...]
0x0000d102:  [P1] = R1;
17748@1473185753.341244:bfin_reg_memory_write write 0x00000050 (<INV>) length 4 with 0x55555561
[...]
0x0000d108:  P1.H = 0xffc0;             /* (-64)        P1=0x0xffc00154(-4193964) */
[...]
0x0000d114:  [P1] = R1;

17748@1473185753.341303:bfin_reg_memory_write write 0x00000054 (<INV>) length 4 with 0x26666656
[...]

» grep SIC_IAR mmr.txt 
0xFFC00110|SIC_IAR0|System Interrupt Assignment (SIC_IAR) Register|5-11
0xFFC00114|SIC_IAR1|System Interrupt Assignment (SIC_IAR) Register|5-11
0xFFC00118|SIC_IAR2|System Interrupt Assignment (SIC_IAR) Register|5-11
0xFFC0011C|SIC_IAR3|System Interrupt Assignment (SIC_IAR) Register|5-11
0xFFC00150|SIC_IAR4|System Interrupt Assignment (SIC_IAR) Register|5-11
0xFFC00154|SIC_IAR5|System Interrupt Assignment (SIC_IAR) Register|5-11
0xFFC00158|SIC_IAR6|System Interrupt Assignment (SIC_IAR) Register|5-11
0xFFC0015C|SIC_IAR7|System Interrupt Assignment (SIC_IAR) Register|5-11