Use meaningful data row names in tst_QTextCodec::fromUnicode test.

Use meaningful data row names in tst_QTextCodec::fromUnicode test.

Use the codec name instead of just numbering the rows. This eliminates
some duplicate row names.  Two duplicate rows have also been removed --
for the WINSAMI2 row, the last value in the row is different, making one
copy do a subset of the testing done by the other, so the row that did
less testing was removed.

Change-Id: I859f681a627e8d3839ca8a4ba09d541bec43d9fb
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>