FatPkg: Fix spelling errors

https://bugzilla.tianocore.org/show_bug.cgi?id=2264

Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>

FatPkg/EnhancedFatDxe/Init.c

@@ -16,7 +16,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
   @param  Handle                - The handle of parent device.
   @param  DiskIo                - The DiskIo of parent device.
   @param  DiskIo2               - The DiskIo2 of parent device.
-  @param  BlockIo               - The BlockIo of parent devicel
+  @param  BlockIo               - The BlockIo of parent device.
 
   @retval EFI_SUCCESS           - Allocate a new volume successfully.
   @retval EFI_OUT_OF_RESOURCES  - Can not allocate the memory.