parisc: Flush gatt writes and adjust gatt mask in parisc_agp_mask_memory()

stable inclusion
from stable-v5.10.185
commit 0ca73b45b767822f1c59c77caefd93e2460778d4
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8L5XP

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0ca73b45b767822f1c59c77caefd93e2460778d4



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[ Upstream commit d7037973 ]

Flush caches after changing gatt entries and calculate entry according
to SBA requirements.

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>