drm/exynos: fix g2d_open/close helper function definitions

stable inclusion
from stable-v5.10.181
commit 01cdda0d27d7c6587e51739a0d6f80d1535b2e4e
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8GJZJ

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=01cdda0d27d7c6587e51739a0d6f80d1535b2e4e



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[ Upstream commit 2ef0785b ]

The empty stub functions are defined as global functions, which
causes a warning because of missing prototypes:

drivers/gpu/drm/exynos/exynos_drm_g2d.h:37:5: error: no previous prototype for 'g2d_open'
drivers/gpu/drm/exynos/exynos_drm_g2d.h:42:5: error: no previous prototype for 'g2d_close'

Mark them as 'static inline' to avoid the warning and to make
them behave as intended.

Fixes: eb4d9796 ("drm/exynos: g2d: Convert to driver component API")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>