usb: gadget: f_fs: Fix wrong check on reserved1 of OS_DESC_EXT_COMPAT

Current __ffs_data_do_os_desc() of f_fs.c will check reserved1 field
of OS_DESC_EXT_COMPAT and return -EINVAL if it's 1.
But MS OS 1.0 Descriptors
http://msdn.microsoft.com/en-us/library/windows/hardware/gg463179.aspx


defines that field to be 1.

Signed-off-by: Jim Lin <jilin@nvidia.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>