[SYCL][Doc] Fix typo in DeviceLibExtension doc (#12008)

This PR fixes typo in devicelib extension doc. In doc, we uses the term
"cl_intel_devicelib_cassert" but we use "cl_intel_devicelib_assert" in
sycl runtime and devicelib implementation. And for other
cl_intel_devicelib_* extension aiming to support CXX std library such as
math and complex functions, we use "cl_intel_devicelib_math",
"cl_intel_devicelib_complex".
To align with other "cl_intel_devicelib_*" extension and sycl runtime&
devicelib implementation, we change "cl_intel_devicelib_cassert" to
"cl_intel_devicelib_assert".

Author: jinge90

sycl/doc/design/DeviceLibExtensions.rst

@@ -4,7 +4,7 @@ Device library extensions
 Device compiler that indicates support for a particular extension is
 supposed to support *all* the corresponding functions.
 
-cl_intel_devicelib_cassert
+cl_intel_devicelib_assert
 ==========================
 
 .. code: