RISC-V: Delete obsolete MIPS comment.

	gcc/
	* config/riscv/riscv.h (FUNCTION_ARG_REGNO_P): Fix comment.

From-SVN: r264652

gcc/ChangeLog

+2018-09-26  Jim Wilson  <jimw@sifive.com>
+
+	* config/riscv/riscv.h (FUNCTION_ARG_REGNO_P): Fix comment.
+
 2018-09-26  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/87414

gcc/config/riscv/riscv.h

@@ -516,8 +516,7 @@ enum reg_class
 #define FUNCTION_VALUE_REGNO_P(N) ((N) == GP_RETURN || (N) == FP_RETURN)
 
 /* 1 if N is a possible register number for function argument passing.
-   We have no FP argument registers when soft-float.  When FP registers
-   are 32 bits, we can't directly reference the odd numbered ones.  */
+   We have no FP argument registers when soft-float.  */
 
 /* Accept arguments in a0-a7, and in fa0-fa7 if permitted by the ABI.  */
 #define FUNCTION_ARG_REGNO_P(N)						\