gba: improve save type detection for homebrew (#1367)

Commercial GBA games contain strings in the ROM that correspond to a
save type (e.g. SRAM, flash memory, EEPROM), followed by 3 digits. These
strings are used by ares to detect what save type to use. However, when
running [jsmolka's SRAM and flash memory save
tests](https://github.com/jsmolka/gba-tests/tree/master/save), ares does
not detect a save type, since the programs lack the 3 digits at the end
of the save type string. This PR ignores the trailing digits during save
type detection, since it's likely that many other homebrew programs are
affected by the same issue ([GBATEK even advises developers to not add
digits when including save type
strings](https://problemkaputt.de/gbatek-gba-cart-backup-ids.htm)).

mia/medium/game-boy-advance.cpp

@@ -71,16 +71,7 @@ auto GameBoyAdvance::analyze(vector<u8>& rom) -> string {
   for(auto& identifier : identifiers) {
     for(s32 n : range(rom.size() - 16)) {
       if(!memory::compare(&rom[n], identifier.data(), identifier.size())) {
-        auto p = (const char*)&rom[n + identifier.size()];
-        if(p[0] >= '0' && p[0] <= '9'
-        && p[1] >= '0' && p[1] <= '9'
-        && p[2] >= '0' && p[2] <= '9'
-        ) {
-          char text[16];
-          memory::copy(text, &rom[n], identifier.size() + 3);
-          text[identifier.size() + 3] = 0;
-          if(!list.find(text)) list.append(text);
-        }
+        if(!list.find(identifier.data())) list.append(identifier.data());
       }
     }
   }