usb: composite: Fix reporting MaxPower as 0xFA instead of 0x70

USB device is reporting MaxPower as 0xFA (i.e. 2000mA) when enumerated
into USB super speed plus mode. Few host may complain about not able to
supply enough power to connected device. Hence fix this issue by
reporting MaxPower as 0x70 (i.e. 896 mA) which is within allowed
current draw limit (i.e. 900mA) of USB specification.

CRs-Fixed: 2217005
Change-Id: Idfef036ed86391ec0aaad6a5b680ed9c90f07abb
Signed-off-by: Mayank Rana <mrana@codeaurora.org>