drm/vc4: Move IRQ enable to PM path

[ Upstream commit ce9caf2f ]

We were calling enable_irq on bind, where it was already enabled previously
by the IRQ helper. Additionally, dev->irq is not set correctly until after
postinstall and so was always zero here, triggering a warning in 4.15.
Fix both by moving the enable to the power management resume path, where we
know there was a previous disable invocation during suspend.

Fixes: 253696cc

 ("drm/vc4: Account for interrupts in flight")
Signed-off-by: Stefan Schake <stschake@gmail.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/1514563543-32511-1-git-send-email-stschake@gmail.com


Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Backported from rpi-14.4.y (fixed merge conflict)

Signed-off-by: Mirza Krak <mirza.krak@northern.tech>