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/code_801068B0.c

@@ -2,13 +2,10 @@
 
 // memcpy used in __osMalloc.c
 void* func_801068B0(void* dst, void* src, size_t size) {
-    u8* spC;
-    u8* sp8;
+    u8* spC = dst;
+    u8* sp8 = src;
     register s32 a3;
 
-    spC = dst;
-    sp8 = src;
-
     if (spC == sp8) {
         return dst;
     }