Fix large file read issue on USB device

The current USB block read library trancated the number of blocks
to read from UINT32 to UINT16. It caused read issue for large file
on USB disk. This patch fixed #63. It has been verified on LeahHill
CRB platform.

Signed-off-by: Maurice Ma <maurice.ma@intel.com>

BootloaderCommonPkg/Library/UsbBlockIoLib/PeiAtapi.c

@@ -378,7 +378,7 @@ PeiUsbRead10 (
   ATAPI_PACKET_COMMAND  Packet;
   ATAPI_READ10_CMD      *Read10Packet;
   UINT16                MaxBlock;
-  UINT16                BlocksRemaining;
+  UINT32                BlocksRemaining;
   UINT16                SectorCount;
   UINT32                Lba32;
   UINT32                BlockSize;
@@ -398,14 +398,14 @@ PeiUsbRead10 (
   BlockSize       = (UINT32) PeiBotDevice->Media.BlockSize;
 
   MaxBlock        = (UINT16) (65535 / BlockSize);
-  BlocksRemaining = (UINT16) NumberOfBlocks;
+  BlocksRemaining = NumberOfBlocks;
 
   Status          = EFI_SUCCESS;
   while (BlocksRemaining > 0) {
 
     if (BlocksRemaining <= MaxBlock) {
 
-      SectorCount = BlocksRemaining;
+      SectorCount = (UINT16)BlocksRemaining;
 
     } else {
 
@@ -456,7 +456,7 @@ PeiUsbRead10 (
 
     Lba32 += SectorCount;
     PtrBuffer       = (UINT8 *) PtrBuffer + SectorCount * BlockSize;
-    BlocksRemaining = (UINT16) (BlocksRemaining - SectorCount);
+    BlocksRemaining = BlocksRemaining - SectorCount;
   }
 
   return Status;