kfdtest: Add a function to wait indefinitely until user input

This will facilitate the need of halting the execution during debugging.

Change-Id: I058c81bbc9f655bbc477b2b542d6b43aa423324c
Signed-off-by: Yong Zhao <Yong.Zhao@amd.com>

tests/kfdtest/src/KFDTestUtil.hpp

@@ -35,6 +35,7 @@ class BaseQueue;
 #define ALIGN_UP(x, align) (((uint64_t)(x) + (align) - 1) & ~(uint64_t)((align)-1))
 #define CounterToNanoSec(x) ((x) * 1000 / (is_dgpu() ? 27 : 100))
 
+void WaitUntilInput();
 uint64_t RoundToPowerOf2(uint64_t val);
 
 // @brief: waits until the value is written to the buffer or until time out if received through args