BugFix:Lost first word from FIFO

    1) Do not overwrite Reserved Bits in GINTSTS (per ref manual)*
    2) Acknowledge all pending int on entry to ISR that are Only rc_w1*
    3) Do not disable RXFVL*
    4) Loop until RXFVL is cleared*
    5) Only clear the NAK on the endpoint on the OTGFS_GRXSTSD_PKTSTS_SETUPDONE to
       not loose the first WORD of FIFO all the data  (Bug Fix)

Changed marked *are just driver clean up and ensure ints are not lost.
The bug fix is #5

Test case open putty and observer the Set/Get LineCoding
Without this fix #5 the Get will not match the Set, and
infact the data might be skewed by 4 bytes, that are lost
from the FIFO if the OTGFS_DOEPCTL0_CNAK bit is set in the
OTGFS_GRXSTSD_PKTSTS_SETUPRECVD as opposed to the OTGFS_GRXSTSD_PKTSTS_SETUPDONE

Set Line Coding DATA1: 4B | 00 c2 01 00 00 00 08 | c8 1B
Get Line Coding DATA1: 4B | .. .. .. .. 00 00 08   c8 .. 00 00 07 | 7a 72