Use labels instead of constants for HRAM

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

engine/phone/phone.asm

@@ -94,7 +94,7 @@ GetRemainingSpaceInPhoneList:
 INCLUDE "data/phone/permanent_numbers.asm"
 
 FarPlaceString:
-	ld a, [hROMBank]
+	ldh a, [hROMBank]
 	push af
 	ld a, b
 	rst Bankswitch
@@ -170,7 +170,7 @@ ChooseRandomCaller:
 ; Sample a random number between 0 and 31.
 	ld c, a
 	call Random
-	ld a, [hRandomAdd]
+	ldh a, [hRandomAdd]
 	swap a
 	and $1f
 ; Compute that number modulo the number of available callers.