phy: renesas: rcar-gen3-usb2: move irq registration to init

phy: renesas: rcar-gen3-usb2: move irq registration to init

If CONFIG_DEBUG_SHIRQ was enabled, r8a77951-salvator-xs could boot
correctly. If we appended "earlycon keep_bootcon" to the kernel
command like, we could get kernel log like below.

    SError Interrupt on CPU0, code 0xbf000002 -- SError
    CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.8.0-rc3-salvator-x-00505-g6c843129e6faaf01 #785
    Hardware name: Renesas Salvator-X 2nd version board based on r8a77951 (DT)
    pstate: 60400085 (nZCv daIf +PAN -UAO BTYPE=--)
    pc : rcar_gen3_phy_usb2_irq+0x14/0x54
    lr : free_irq+0xf4/0x27c

This means free_irq() calls the interrupt handler while PM runtime
is not getting if DEBUG_SHIRQ is enabled and rcar_gen3_phy_usb2_probe()
failed. To fix the issue, move the irq registration place to
rcar_gen3_phy_usb2_init() which is ready to handle the interrupts.

Note that after the commit 549b6b55b005 ("phy: renesas: rcar-gen3-usb2:
enable/disable independent irqs") which is merged into v5.2, since this
driver creates multiple phy instances, needs to check whether one of
phy instances is initialized. However, if we backport this patch to v5.1
or less, we don't need to check it because such kernel have single
phy instance.

Reported-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Fixes: 9f391c574efc ("phy: rcar-gen3-usb2: add runtime ID/VBUS pin detection")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/1594986297-12434-2-git-send-email-yoshihiro.shimoda.uh@renesas.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>