aarch64: Allow testing for the presence of SVE FEAT_EBF16 (#57)

Allows testing the new hwcap for determining SVE support for extended
BFloat16 behavior on Linux systems.
diff --git a/src/cpu-features.h b/src/cpu-features.h
index de9e157..962ad52 100644
--- a/src/cpu-features.h
+++ b/src/cpu-features.h
@@ -199,7 +199,8 @@
   /* WFET and WFIT instruction support                                      */ \
   V(kWFXT,                "WFXT",                   "wfxt")                    \
   /* Extended BFloat16 instructions                                         */ \
-  V(kEBF16,               "EBF16",                  "ebf16")
+  V(kEBF16,               "EBF16",                  "ebf16")                   \
+  V(kSVE_EBF16,           "EBF16 (SVE)",            "sveebf16")
 // clang-format on