Fix getting bitwidth of PointerType of LLVM.
Fix getting bitwidth of PointerType of LLVM.

PointerType could not be forced to IntegerTyoe for getting bitwidth.
With Rong's comments, use getTypeBitSize() instead of
Type::getIntegerBitWidth().

Signed-off-by: Yan Wang <8ca54580088a7ffe1dd243d1c16c6d1f04463d55@linux.intel.com>
Reviewed-by: Yang Rong <78759e37dc7114caed18f74e7515c5cb519dbf6d@intel.com>

wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet