OMAP4: MUSB: peripheral isoch in transfer support

This patch fixes the following
1. The logic that determines a short packet endpoint sizes to be a power of
   2 number. This is typically not true for isochronous endpoints.
2. When a short/zero packet or DMA mode 0 is used, and TXPKTRDY is needed to
   be set by the CPU, the ISO bit should be set if its an isochronous transfer.
3. When a short/zero packet or DMA mode 0 is used, and TXPKTRDY is set by the
   CPU, g_giveback_request is deferred till the endpoint interrupt occurs.

Change-Id: I87873496b90755cf78fd283ca996f17f02408dcd
Signed-off-by: Ruchika Kharwar <ruchika@ti.com>

Conflicts:
	drivers/usb/musb/musb_gadget.c