Replace ‘jp [hl]’ with ‘jp hl’

The former is arguably misleading (as you don’t access the memory location in hl to retrieve the jump location), and is consequently deprecated in newer versions of rgbds.

This fix silences these deprecation warnings.

battle/bg_effects.asm

@@ -75,7 +75,7 @@ DoBattleBGEffectFunction: ; c804a (32:404a)
 	ld a, [hli]
 	ld h, [hl]
 	ld l, a
-	jp [hl]
+	jp hl
 
 BattleBGEffects: ; c805a (32:405a)
 	dw BattleBGEffect_End
@@ -161,7 +161,7 @@ BattleBGEffects_AnonJumptable: ; c80d7 (32:40d7)
 	ld a, [hli]
 	ld h, [hl]
 	ld l, a
-	jp [hl]
+	jp hl
 
 BattleBGEffects_IncrementJumptable: ; c80e5 (32:40e5)
 	ld hl, BG_EFFECT_STRUCT_JT_INDEX
@@ -2059,7 +2059,7 @@ BattleBGEffect_1c: ; c8b00 (32:4b00)
 .cgb
 	ld de, .Jumptable
 	call BatttleBGEffects_GetNamedJumptablePointer
-	jp [hl]
+	jp hl
 
 .Jumptable:
 	dw .cgb_zero
@@ -2421,7 +2421,7 @@ BGEffect_RapidCyclePals: ; c8d77 (32:4d77)
 	ld de, .Jumptable_DMG
 	call BatttleBGEffects_GetNamedJumptablePointer
 	pop de
-	jp [hl]
+	jp hl
 
 .Jumptable_DMG:
 	dw .zero_dmg
@@ -2484,7 +2484,7 @@ BGEffect_RapidCyclePals: ; c8d77 (32:4d77)
 	ld de, .Jumptable_CGB
 	call BatttleBGEffects_GetNamedJumptablePointer
 	pop de
-	jp [hl]
+	jp hl
 
 .Jumptable_CGB: ; c8ddd (32:4ddd)
 	dw .zero_cgb