Fixed Slide Code cheat type

Address increment is a u8 and value increment is a u16. The changes will make this work correctly:-

50000AA4 FFFF
801CC760 0400
which is a example slide code representing:-
801CC760 0400
801CC804 03FF
801CC8A8 03FE
801CC94C 03FD
801CC9F0 03FC
801CCA94 03FB
801CCB38 03FA
801CCBDC 03F9
801CCC80 03F8
801CCD24 03F7

src/core/cheats.cpp

@@ -1144,8 +1144,8 @@ void CheatCode::Apply() const
         }
 
         const u32 slide_count = (inst.first >> 8) & 0xFFu;
-        const u32 address_increment = SignExtendN<8>(inst.first & 0xFFu);
-        const u16 value_increment = SignExtendN<8>(Truncate16(inst.second & 0xFFu));
+        const u32 address_increment = inst.first & 0xFFu;
+        const u16 value_increment = Truncate16(inst.second);
         const Instruction& inst2 = instructions[index + 1];
         const InstructionCode write_type = inst2.code;
         u32 address = inst2.address;