Use labels instead of constants for HRAM

Use explicit ldh instruction to access HRAM locations, don't rely on optimizing ld

engine/pokemon/party_menu.asm

@@ -46,7 +46,7 @@ WritePartyMenuTilemap:
 	push af
 	set NO_TEXT_SCROLL, [hl]
 	xor a
-	ld [hBGMapMode], a
+	ldh [hBGMapMode], a
 	hlcoord 0, 0
 	ld bc, SCREEN_WIDTH * SCREEN_HEIGHT
 	ld a, " "
@@ -590,7 +590,7 @@ InitPartyMenuGFX:
 	ret z
 	ld c, a
 	xor a
-	ld [hObjectStructIndexBuffer], a
+	ldh [hObjectStructIndexBuffer], a
 .loop
 	push bc
 	push hl
@@ -598,9 +598,9 @@ InitPartyMenuGFX:
 	ld a, BANK(LoadMenuMonIcon)
 	ld e, MONICON_PARTYMENU
 	rst FarCall
-	ld a, [hObjectStructIndexBuffer]
+	ldh a, [hObjectStructIndexBuffer]
 	inc a
-	ld [hObjectStructIndexBuffer], a
+	ldh [hObjectStructIndexBuffer], a
 	pop hl
 	pop bc
 	dec c
@@ -682,7 +682,7 @@ PartyMenuSelect:
 	cp b
 	jr z, .exitmenu ; CANCEL
 	ld [wPartyMenuCursor], a
-	ld a, [hJoyLast]
+	ldh a, [hJoyLast]
 	ld b, a
 	bit B_BUTTON_F, b
 	jr nz, .exitmenu ; B button