Correct ld.texinfo cross reference

Fixes
warning: @pxref cross-reference name should not contain `:'

	* ld.texinfo (Options <--defsym>): Correct cross reference.

ld/ChangeLog

@@ -1,3 +1,7 @@
+2015-02-13  Alan Modra  <amodra@gmail.com>
+
+	* ld.texinfo (Options <--defsym>): Correct cross reference.
+
 2015-02-11  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* lexsup.c (ld_options): Add --[no-]map-whole-files for gold

ld/ld.texinfo

@@ -1372,10 +1372,9 @@ limited form of arithmetic is supported for the @var{expression} in this
 context: you may give a hexadecimal constant or the name of an existing
 symbol, or use @code{+} and @code{-} to add or subtract hexadecimal
 constants or symbols.  If you need more elaborate expressions, consider
-using the linker command language from a script (@pxref{Assignments,,
-Assignment: Symbol Definitions}).  @emph{Note:} there should be no white
-space between @var{symbol}, the equals sign (``@key{=}''), and
-@var{expression}.
+using the linker command language from a script (@pxref{Assignments}).
+@emph{Note:} there should be no white space between @var{symbol}, the
+equals sign (``@key{=}''), and @var{expression}.
 
 @cindex demangling, from command line
 @kindex --demangle[=@var{style}]