sys/modules/acpi/Makefile: One line per subdirectory

This makes diffs that add or remove modules easier to read.

Reviewed by:	imp
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D54314

sys/modules/acpi/Makefile

@@ -1,5 +1,17 @@
-SUBDIR=		acpi_asus acpi_asus_wmi acpi_dock acpi_fujitsu acpi_hp	\
-		acpi_ged acpi_ibm acpi_panasonic acpi_sbl_wmi acpi_sony	\
-		acpi_toshiba acpi_video acpi_wmi aibs
+SUBDIR=	\
+	acpi_asus \
+	acpi_asus_wmi \
+	acpi_dock \
+	acpi_fujitsu \
+	acpi_ged \
+	acpi_hp \
+	acpi_ibm \
+	acpi_panasonic \
+	acpi_sbl_wmi \
+	acpi_sony \
+	acpi_toshiba \
+	acpi_video \
+	acpi_wmi \
+	aibs
 
 .include <bsd.subdir.mk>