drivers: mailbox: qti-tcs: Remove error handling

When an RPMH request is sent, an error response is set up as delayed wq.
When an interrupt response is received for the request, the delayed work
is cancelled. If the interrupt response did not turn up, the delayed
work will responsd back with -ETIMEDOUT value.

However, the situation becomes complex when debugging with a JTAG
debugger. If the Core0 debugger stops the CPU, the interrupt may not be
handled and therefore the delayed workq would not be cancelled. The
delayed work may be scheduled in another CPU and would send a response
back the calling thread. When the debugger releases the hold on the
Core0, it would execute the interrupt handler, which may try to look for
the same response object but would not find it. This race condition is
hard to solve. Remove the error response itself. If for some reason, we
do not get an interrupt from the RPMH, we will hang the calling driver,
which should give us enough information to debug.

Change-Id: I58f2ee1cdde763dcc10d1573b349d3c72fb5d09e
Signed-off-by: Lina Iyer <ilina@codeaurora.org>