Fix most compiler warnings in the boot and code segments (#674)

* Less warnings in boot & code segments

* few more warnings gone

* Ran formatter

* z_view warning gone

* -> 1

* f31 -> 31

* Remove function casts

* Few more small improvements

* Separate declaration and assignment in func_80091738 and Item_Give

Co-authored-by: Thar0 <maximilianc64@gmail.com>

src/code/sys_cfb.c

@@ -6,6 +6,7 @@ u32 sSysCfbEnd;
 void SysCfb_Init(s32 n64dd) {
     u32 screenSize;
     u32 tmpFbEnd;
+
     if (osMemSize >= 0x800000U) {
         // 8MB or more memory is installed
         osSyncPrintf("８Ｍバイト以上のメモリが搭載されています\n");