Remove patch that enabled write caching of usb drives and mSD Card

This  removes a patch that was being applied that changed the default mount behaviour of "sync" to "dirsync".   This is bad, as ultimately leads to disk corruption.

This is potentially the lesser of two evils.  There is no method in XBMC to enable the safe removable of USB media or mSD card.

With write cache enabled it can be up to 30 seconds from actual change, before the data is flushed to disk.  This problematic on this platform that at this time doesn't have a real shutdown option.  It is one thing when corruption occurs on mSD card, its another when corruption destroys the volume on a 2TB usb drive.

Improper removable of media or shutdown without a flush of the disk write cache can cause disk corruption for external USB drives on suspend of an M3, corruption of mSD card on a hard reboot on M1 and M3, and can cause file systems to ultimately end up mounting read only.

Running with "sync" enabled on usb storage can in theory shorten life of storage device but is better than constant problem of disk corruption.  This also will have some impact on performance during disk writes.