[ARC] Update mea option documentation

Update -mea option documentation.

gcc/
xxxx-xx-xx  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/arc.opt (mea): Update help string.
	* doc/invoke.texi(ARC): Update mea option info.

From-SVN: r277884

gcc/ChangeLog

 2019-11-06  Claudiu Zissulescu  <claziss@synopsys.com>
 
+	* config/arc/arc.opt (mea): Update help string.
+	* doc/invoke.texi(ARC): Update mea option info.
+
+2019-11-06  Claudiu Zissulescu  <claziss@synopsys.com>
+
 	* config/arc/arc.md (zero_extendqihi2_i): Cleanup pattern.
 	(zero_extendqisi2_ac): Likewise.
 	(zero_extendhisi2_i): Likewise.

gcc/config/arc/arc.opt

@@ -175,7 +175,7 @@ Do not generate mpy instructions for ARC700.
 
 mea
 Target Report Mask(EA_SET)
-Generate Extended arithmetic instructions.  Currently only divaw, adds, subs and sat16 are supported.
+Generate extended arithmetic instructions, only valid for ARC700.
 
 msoft-float
 Target Report Mask(0)

gcc/doc/invoke.texi

@@ -16627,7 +16627,7 @@ aux registers.
 @opindex mea
 Generate extended arithmetic instructions.  Currently only
 @code{divaw}, @code{adds}, @code{subs}, and @code{sat16} are
-supported.  This is always enabled for @option{-mcpu=ARC700}.
+supported.  Only valid for @option{-mcpu=ARC700}.
 
 @item -mno-mpy
 @opindex mno-mpy