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

Fix the warning below by making the integer literal unsigned.

```
    CC         bootblock/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));
                            ~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
```

Found-by: Clang static analyzer scan-build
          (clang version 4.0.1-6 (tags/RELEASE_401/final))
Fixes: e237f8b7 (soc/apollolake/lpc: Open I/O to LPC based on resource allocation)

Change-Id: I094fb469f020f3c1fae936e304b4458858842a8e
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-on: https://review.coreboot.org/22198
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
diff --git a/src/soc/intel/common/block/fast_spi/fast_spi.c b/src/soc/intel/common/block/fast_spi/fast_spi.c
index 87cafb9..1d3a3c8 100644
--- a/src/soc/intel/common/block/fast_spi/fast_spi.c
+++ b/src/soc/intel/common/block/fast_spi/fast_spi.c
@@ -230,7 +230,7 @@
 		return;
 
 	/* Round to power of two */
-	alignment = 1 << (log2_ceil(bios_size));
+	alignment = 1UL << (log2_ceil(bios_size));
 	bios_size = ALIGN_UP(bios_size, alignment);
 	base = 4ULL*GiB - bios_size;