media: video: fixed memory leak for sure

So there was happening some memory leak inside the
camera device driver:
unreferenced object 0xde5a2180 (size 128):
  comm "swapper", pid 1, jiffies 4294929160
  hex dump (first 32 bytes):
    80 21 5a de 80 21 5a de 68 a1 25 c0 a4 a0 25 c0  .!Z..!Z.h.%...%.
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<c00e6774>] kmem_cache_alloc+0xb4/0xc0
    [<c025ac78>] device_private_init+0x14/0x4c
    [<c025ced8>] dev_set_drvdata+0x20/0x34
    [<c0300504>] omap34xxcam_device_register+0x1e4/0x2a8
    [<c02f7d54>] v4l2_int_device_try_attach_all+0x100/0x148
    [<c02f7df4>] v4l2_int_device_register+0x58/0x70
    [<c00237c8>] omap34xxcam_init+0xbc/0x108
    [<c004b37c>] do_one_initcall+0x5c/0x1b8
    [<c00083f8>] kernel_init+0x98/0x110
    [<c004c99c>] kernel_thread_exit+0x0/0x8
    [<ffffffff>] 0xffffffff

As seen in this commit 34f4bafbf87d4db582c6a4ca1ed57dcc81758b39 my
first attention was to free up cam if it fails to init. Obviously
this was the wrong way and @Musiker made some suggestions to really
fix this (thanks!). omap34xxcam!=NULL would be never called since it has got
only one init.
As hinted in the memory leak report, its somehow dev_set_drvdata()'s fault.
Because it gets called before the v4l2 device is registered properly and
therefore the device structure got zeroed after this. So reference is lost
and memory leak is happening.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>