[media] exynos4-is: Ensure the FIMC gate clock is disabled at driver remove()

[media] exynos4-is: Ensure the FIMC gate clock is disabled at driver remove()

The patch fixes following warning:
[ 9664.460000] WARNING: CPU: 0 PID: 2880 at drivers/clk/clk.c:695 __clk_unprepare+0x8c/0xa4()
[ 9664.470000] Modules linked in: m5mols s5k5baf s5p_fimc(-) ipv6 s5p_csis v4l2_mem2mem videobuf2_dma_contig videobuf2_memops exynos4_is_common videobuf2_core [last unloaded: m5mols]
[ 9664.485000] CPU: 0 PID: 2880 Comm: rmmod Tainted: G        W    3.11.0-rc1-00070-ga94e22f-dirty #1558
[ 9664.495000] [<c0014aec>] (unwind_backtrace+0x0/0xf8) from [<c0011574>] (show_stack+0x10/0x14)
[ 9664.505000] [<c0011574>] (show_stack+0x10/0x14) from [<c038b248>] (dump_stack+0x6c/0xac)
[ 9664.510000] [<c038b248>] (dump_stack+0x6c/0xac) from [<c001d824>] (warn_slowpath_common+0x64/0x88)
[ 9664.520000] [<c001d824>] (warn_slowpath_common+0x64/0x88) from [<c001d864>] (warn_slowpath_null+0x1c/0x24)
[ 9664.530000] [<c001d864>] (warn_slowpath_null+0x1c/0x24) from [<c02f0b9c>] (__clk_unprepare+0x8c/0xa4)
[ 9664.540000] [<c02f0b9c>] (__clk_unprepare+0x8c/0xa4) from [<c02f0bc8>] (clk_unprepare+0x14/0x1c)
[ 9664.550000] [<c02f0bc8>] (clk_unprepare+0x14/0x1c) from [<bf191344>] (fimc_clk_put+0x3c/0x5c [s5p_fimc])
[ 9664.560000] [<bf191344>] (fimc_clk_put+0x3c/0x5c [s5p_fimc]) from [<bf1913c0>] (fimc_remove+0x5c/0x90 [s5p_fimc])
[ 9664.570000] [<bf1913c0>] (fimc_remove+0x5c/0x90 [s5p_fimc]) from [<c0219ca0>] (platform_drv_remove+0x18/0x1c)
[ 9664.580000] [<c0219ca0>] (platform_drv_remove+0x18/0x1c) from [<c021856c>] (__device_release_driver+0x70/0xcc)
[ 9664.590000] [<c021856c>] (__device_release_driver+0x70/0xcc) from [<c0218d54>] (driver_detach+0xac/0xb0)
[ 9664.595000] [<c0218d54>] (driver_detach+0xac/0xb0) from [<c021839c>] (bus_remove_driver+0x7c/0xc0)
[ 9664.605000] [<c021839c>] (bus_remove_driver+0x7c/0xc0) from [<c00659d8>] (SyS_delete_module+0x11c/0x204)
[ 9664.615000] [<c00659d8>] (SyS_delete_module+0x11c/0x204) from [<c000e360>] (ret_fast_syscall+0x0/0x30)
[ 9664.625000] ---[ end trace 662c092cce432c8d ]---

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>