phy: rockchip: Fix return value of inno_dsidphy_probe()

When call function devm_platform_ioremap_resource(), we should use IS_ERR()
to check the return value and return PTR_ERR() if failed.

Fixes: b7535a3b ("phy/rockchip: Add support for Innosilicon MIPI/LVDS/TTL PHY")
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/1590412138-13903-1-git-send-email-yangtiezhu@loongson.cn


Signed-off-by: Vinod Koul <vkoul@kernel.org>