[SYCL][DOC] DeviceLib doc update to add new supported items

[jinge90]

Signed-off-by: gejin ge.jin@intel.com

[bader]

@jinge90, could you remind me PR/commit IDs where these functions were added, please?

[jinge90]

@jinge90, could you remind me PR/commit IDs where these functions were added, please?

Hi, @bader
#3262 is for adding support div, ldiv, lldiv.
#3364 is for adding support abs, labs,llabs

And a bunch of math functions are removed from list of math function unsupported although we didn't add any support in SYCL device library. The reason is those math functions are converted to corresponding llvm intrinsic and llvm-spirv has supported those intrinsic, so they can work in SYCL device now, The corresponding PR is: KhronosGroup/SPIRV-LLVM-Translator#855
Thanks very much.

[bader]

Thanks, but I can't find scalbn and nextafter implementations in provided PRs.

[jinge90]

Thanks, but I can't find scalbn and nextafter implementations in provided PRs.

Hi, @bader
For scalbn, we added long time ago but didn't update the doc
#2558

For nextafter, I think it was a mistake in initial version of the doc, this API was added long time ago in the first patch for cmath, complex device library, #975
Thanks very much.

[jinge90]

Hi, @intel/dpcpp-specification-reviewers
Could you help review this change?
Thanks very much.

[jinge90]

Add @pvchupin
Thanks very much.

[gmlueck]

LGTM.