[SYCL] Update test scripts and sycl-ls to use 'fpga' with ONEAPI_DEVICE_SELECTOR (#12596)

As per the ONEAPI_DEVICE_SELECTOR
[documentation](https://github.com/intel/llvm/blob/sycl/sycl/doc/EnvironmentVariables.md#oneapi_device_selector),
the device type can only be cpu, gpu, or fpga (or any combination of
those). Currently, 'acc' is also accepted by ONEAPI_DEVICE_SELECTOR as a
valid device type, which is incorrect.

This PR modifies lit.cfg.py and sycl-ls to use 'fpga' instead of 'acc'
in ONEAPI_DEVICE_SELECTOR.

Author: uditagarwal97

sycl/test-e2e/lit.cfg.py

@@ -427,7 +427,7 @@
 config.sycl_devices = [x.replace("ext_oneapi_", "") for x in config.sycl_devices]
 
 available_devices = {
-    "opencl": ("cpu", "gpu", "acc"),
+    "opencl": ("cpu", "gpu", "fpga"),
     "cuda": "gpu",
     "level_zero": "gpu",
     "hip": "gpu",

sycl/tools/sycl-ls/sycl-ls.cpp

@@ -49,7 +49,7 @@ std::string getDeviceTypeName(const device &Device) {
   case info::device_type::host:
     return "host";
   case info::device_type::accelerator:
-    return "acc";
+    return "fpga";
   default:
     return "unknown";
   }