soc/intel/common/block/lpc: Make integer literal unsigned long

```
    CC         romstage/soc/intel/common/block/*/lpc_lib.o
src/soc/intel/common/block/lpc/lpc_lib.c:91:17: warning: The result of the '<<' expression is undefined
                alignment = 1 << (log2_ceil(window_size));
                            ~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
```

Change-Id: I9bf2283e23ca7739a7e5b0993d9b6034ea28fb78
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-on: https://review.coreboot.org/22201
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>

src/soc/intel/common/block/lpc/lpc_lib.c

@@ -88,7 +88,7 @@ void lpc_open_pmio_window(uint16_t base, uint16_t size)
 		window_size = MIN(size, LPC_LGIR_MAX_WINDOW_SIZE);
 
 		/* Window size must be a power of two for the AMASK to work. */
-		alignment = 1 << (log2_ceil(window_size));
+		alignment = 1UL << (log2_ceil(window_size));
 		window_size = ALIGN_UP(window_size, alignment);
 
 		/* Address[15:2] in LGIR[15:12] and Mask[7:2] in LGIR[23:18]. */