Input: stmfts - do not leave device disabled in stmfts_input_open

The commit 26623eea attempted to deal with potential leak of runtime
PM counter when opening the touchscreen device, however it ended up
erroneously dropping the counter in the case of successfully enabling the
device.

Let's address this by using pm_runtime_resume_and_get() and then executing
pm_runtime_put_sync() only when we fail to send "sense on" command to the
device.

Fixes: 26623eea ("Input: stmfts - fix reference leak in stmfts_input_open")
Reported-by: Pavel Machek <pavel@denx.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>