[vbox] Enable some more features now that we have LZMA compression

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/config/vbox/general.h

 /* Disabled from config/defaults/pcbios.h */
 
-#undef IMAGE_ELF
 #undef SANBOOT_PROTO_ISCSI
 #undef SANBOOT_PROTO_AOE
 #undef SANBOOT_PROTO_IB_SRP
 #undef SANBOOT_PROTO_FCP
-#undef REBOOT_CMD
-#undef CPUID_CMD
 
 /* Disabled from config/general.h */
 
-#undef DOWNLOAD_PROTO_HTTP
 #undef CRYPTO_80211_WEP
 #undef CRYPTO_80211_WPA
 #undef CRYPTO_80211_WPA2
 #undef IWMGMT_CMD
-#undef FCMGMT_CMD
-#undef SANBOOT_CMD
 #undef MENU_CMD
-#undef LOGIN_CMD
-#undef SYNC_CMD
 
 /* Ensure ROM banner is not displayed */