arm64: implement bs_sr_<N>

Implement the bs_sr_<N> generic functions based on the generic
mips implementation calling the generic bs_w_<N> functions in a loop.

ral(4) (rt2860.c) panics in RAL_SET_REGION_4() because bs_sr_4()
is NULL.  It seems ral(4) and ti(4) might be the only consumers of
these functions I could find quickly so keeping them in C rather than asm.

Reported by:	Steve Wheeler (https://redmine.pfsense.org/issues/11021)
Reviewed by:	mmel
MFC after:	3 days

sys/arm64/arm64/bus_machdep.c

@@ -128,6 +128,50 @@ generic_bs_subregion(void *t, bus_space_handle_t bsh, bus_size_t offset,
 	return (0);
 }
 
+/*
+ * Write `count' 1, 2, 4, or 8 byte value `val' to bus space described
+ * by tag/handle starting at `offset'.
+ */
+static void
+generic_bs_sr_1(void *t, bus_space_handle_t bsh,
+    bus_size_t offset, uint8_t value, size_t count)
+{
+	bus_addr_t addr = bsh + offset;
+
+	for (; count != 0; count--, addr++)
+		generic_bs_w_1(t, bsh, addr, value);
+}
+
+static void
+generic_bs_sr_2(void *t, bus_space_handle_t bsh,
+		       bus_size_t offset, uint16_t value, size_t count)
+{
+	bus_addr_t addr = bsh + offset;
+
+	for (; count != 0; count--, addr += 2)
+		generic_bs_w_2(t, bsh, addr, value);
+}
+
+static void
+generic_bs_sr_4(void *t, bus_space_handle_t bsh,
+    bus_size_t offset, uint32_t value, size_t count)
+{
+	bus_addr_t addr = bsh + offset;
+
+	for (; count != 0; count--, addr += 4)
+		generic_bs_w_4(t, bsh, addr, value);
+}
+
+static void
+generic_bs_sr_8(void *t, bus_space_handle_t bsh, bus_size_t offset,
+    uint64_t value, size_t count)
+{
+	bus_addr_t addr = bsh + offset;
+
+	for (; count != 0; count--, addr += 8)
+		generic_bs_w_8(t, bsh, addr, value);
+}
+
 struct bus_space memmap_bus = {
 	/* cookie */
 	.bs_cookie = NULL,
@@ -187,10 +231,10 @@ struct bus_space memmap_bus = {
 	.bs_sm_8 = NULL,
 
 	/* set region */
-	.bs_sr_1 = NULL,
-	.bs_sr_2 = NULL,
-	.bs_sr_4 = NULL,
-	.bs_sr_8 = NULL,
+	.bs_sr_1 =	generic_bs_sr_1,
+	.bs_sr_2 =	generic_bs_sr_2,
+	.bs_sr_4 =	generic_bs_sr_4,
+	.bs_sr_8 =	generic_bs_sr_8,
 
 	/* copy */
 	.bs_c_1 = NULL,