ami: Fix ami_parse_bdf() discarding const from strchr() result

[amd-vserbu]

Summary

ami_parse_bdf() stores the result of strchr() (called on a const char *) into a non-const char *. This discards the const qualifier. It was silently accepted on older toolchains but is a hard error when building in C23 mode against glibc ≥ 2.41 (e.g. GCC 15 / Ubuntu 26.04), where <string.h> provides the C23 const-correct strchr overloads. Since sw/AMI/api/Makefile builds with -Wall -Werror, the warning is fatal.

Change

-    char *c = NULL;
+    const char *c = NULL;

in sw/AMI/api/src/ami.c (ami_parse_bdf()). c only ever holds the strchr result and is used for a null check and the pointer subtraction (c - bdf); it is never used to mutate the string, so const char * is correct in all language modes.

Diagnostic (before)

ami.c:392:11: error: assignment discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
  392 |         c = strchr(bdf, ':');
      |           ^
cc1: all warnings being treated as errors

Why now

glibc 2.41 added C23 const-correct overloads for strchr (returns const char * for a const char * argument). The same GCC 14 passes -std=gnu23 against glibc 2.39 but fails against glibc 2.43, so this is a glibc/standard-mode interaction, not a single GCC version. -std=gnu17 and earlier are unaffected.

Testing

Compiled sw/AMI/api with -Wall -Werror across GCC 11–15 and glibc 2.39 / 2.43, in default, -std=gnu17, and -std=gnu23 modes. The change compiles cleanly in every combination; the original code fails only under C23 + glibc ≥ 2.41.

[amd-vserbu]

This addresses issue #39