PCI: dra7xx: Disable pm_runtime on get_sync failure

Fix the error handling when pm_runtime_get_sync() fails.

If pm_runtime_get_sync() fails, call pm_runtime_disable() so there are no
unbalanced pm_runtime_enable() calls.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jingoo Han <jingoohan1@gmail.com>