Fix middle-end/102395: reg_class having only NO_REGS and ALL_REGS.

So this is a simple fix is to just add to the assert that
sclass and dclass are both greater than or equal to NO_REGS.
NO_REGS is documented as the first register class so it should
have the value of 0.

gcc/ChangeLog:

	* lra-constraints.c (check_and_process_move): Assert
	that dclass and sclass are greater than or equal to NO_REGS.