removing extra blank line in ELPA doxygen example code

This is present in master as well and probably causes the example code
not being gnerated completely by doxygen, as it is seen in the webpages

src/elpa.F90

@@ -125,7 +125,6 @@
 !>   if (success != ELPA_OK) then
 !>     print *,"Could not set entry"
 !>   endif
-
 !>   call elpa%set("nev", nev, success, success)
 !>   ! check success code ...
 !>