PR gas/15082
* tic6x-opcode-table.h: Rename mpydp's specific operand type macro
from ORREGD1324 to ORXREGD1324 and make it cross-path-able through
tic6x_operand_xregpair operand coding type.
Make mpydp instruction cross-path-able, ie: remove the FIXed 'x'
opcode field, usu ORXREGD1324 for the src2 operand and remove the
TIC6X_FLAG_NO_CROSS.
* gas/tic6x/insns-bad-1.s: Remove test-case for mpydp with
cross-path.
* gas/tic6x/insns-bad-1.l: Update expected output.
* gas/tic6x/insns-c674x.s: Add a test-case for mpydp with
cross-path.
* gas/tic6x/insns-c674x.d: Update expected output.