drm/i915/gt: Increase a time to retry RING_HEAD reset

Issue seen again where engine resets fails because the engine resumes from
an incorrect RING_HEAD. HEAD is still not 0 even after writing into it.
This seems to be timing issue and we experimented different values from 5ms
to 50ms and found out that 50ms works best based on testing.
So, if write doesn't succeed at first then retry again.

v2: add a comment (Andi Shyti)

Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/12806


Signed-off-by: Nitin Gote <nitin.r.gote@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241217063532.2729031-1-nitin.r.gote@intel.com