malta uhci quirks: make allowance for slow 4k(e)c

This works around an unexpected IRQ #255 seen during initial USB host
mass storage device initialization and access.
* wait up to 50us for HCRESET to clear, a slow 4kc needs a longer time.
* leave FSBR enabled so that a slow 4kec/24kec will not be overwhelmed.

Signed-off-by: <weixing.shil@windriver.com> Weixing Shi
Signed-off-by: <bruce.ashfield@windriver.com> Bruce Ashfield