bluetooth: btbcm: Fix logic error in forming the board name.

This patch fixes an incorrect loop exit condition in code that replaces
'/' symbols in the board name. There might also be a memory corruption
issue here, but it is unlikely to be a real problem.

Cc: <stable@vger.kernel.org>
Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>