usb: gadget: tegra-xudc: Fix error check in tegra_xudc_powerdomain_init()

usb: gadget: tegra-xudc: Fix error check in tegra_xudc_powerdomain_init()

[ Upstream commit f7de7dca8d8674a2afdf7f64af8a0244d3938be8 ]

dev_pm_domain_attach_by_name() may return NULL in some cases,
so IS_ERR() doesn't meet the requirements. Thus fix it.

Fixes: f4e304b872e7 ("usb: gadget: Add UDC driver for tegra XUSB device mode controller")
Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20220525135332.23144-1-tangbin@cmss.chinamobile.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>