Performs a MULA operation with contents of registers Rs1 and
Rs2, then loads the result into AGU accumulator register. Both
registers are accessed via port 5 with their banks selected by
BS5.
Takes 6 cycles to execute.
Example: AGU_RXR 0x50 0x51
AGU P5
-------
- 50
- 51
- 00
RXR 00
- 00
- 00
NOT YET
AGU_RXR 0x20 0x21
!! Performs MULA with contents
!! of registers 0x20 and 0x21
!! then load the result to AGU
!! accumulator register.