loader.efi: Fix build with gcc due to pointer / int issues on 32-bit build

[imp]

Summary

Use (uintptr_t) casts to cast the EFI_PHYSICAL_ADDDRESS to a pointer.

Fixes: afee781523e4 ("loader.efi: Recognize new memdisk=<url> and memcd=<url> options")
Sponsored by: Netflix

[rlibby]

Logic LGTM.

I guess we don't follow 80 column limit in this file?

For my education: do we know in the 32-bit environment that physical addresses assuredly are below 4 GB?

[imp]

Yea. I don't care about 80 columns for the boot loader. It's obsolete and makes the code ugly. I usually wrap around 100 chars..

[imp]

In D57893#1327224, @rlibby wrote:

For my education: do we know in the 32-bit environment that physical addresses assuredly are below 4 GB?

Yes. There's only 32-bits, it necessarily has to be below 4GB and has other limits.