Rename algo variants again, should be final numbers.

options.h

@@ -35,12 +35,10 @@
 enum xmr_algo_variant {
     XMR_AV0_AUTO,
     XMR_AV1_AESNI,
-    XMR_AV2_AESNI_BMI2,
-    XMR_AV3_AESNI_ALT,
+    XMR_AV2_STAK,
+    XMR_AV3_AESNI_BMI2,
     XMR_AV4_SOFT_AES,
-    XMR_AV5_STAK,
-    XMR_AV6_STAK_NO_PREFETCH,
-    XMR_AV7_EXPERIMENTAL,
+    XMR_AV5_EXPERIMENTAL,
     XMR_AV_MAX
 };