Remove presumably dead < USHRT_MAX checks

...which are proably obsolete since 17e2497b
"INTEGRATION: CWS tl39: #i77024# chart2 with more than 26 columns" changed the
members of SwRangeDescriptor from sal_uInt16 to sal_Int32.

Change-Id: Ic383bc2d5f686af5b19a5ec2cd0351607958f672
Reviewed-on: https://gerrit.libreoffice.org/48470Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

sw/source/core/unocore/unotbl.cxx

@@ -2263,7 +2263,7 @@ uno::Reference<table::XCellRange>  SwXTextTable::getCellRangeByPosition(sal_Int3
 {
     SolarMutexGuard aGuard;
     SwFrameFormat* pFormat(GetFrameFormat());
-    if(pFormat && nRight < USHRT_MAX && nBottom < USHRT_MAX &&
+    if(pFormat &&
             nLeft <= nRight && nTop <= nBottom &&
             nLeft >= 0 && nRight >= 0 && nTop >= 0 && nBottom >= 0 )
     {