drivers/video/exynos/exynos_mipi_dsi.c: fix an error check condition

drivers/video/exynos/exynos_mipi_dsi.c: fix an error check condition

Checking an unsigned variable for negative value returns false.  Hence use
the macro to fix it.

Fixes the following smatch warning:

  drivers/video/exynos/exynos_mipi_dsi.c:417 exynos_mipi_dsi_probe() warn: unsigned 'dsim->irq' is never less than zero.

Signed-off-by: Sachin Kamat <[email protected]>
Acked-by: Donghwa Lee <[email protected]>
Cc: Inki Dae <[email protected]>
Cc: Florian Tobias Schandinat <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>