configs/mx53loco: Bump to kernel 4.17.4

Kernel 4.17.4 contains commit 32c319d4f120 ("pinctrl: devicetree: Fix
pctldev pointer overwrite"), which fixes audio support
on imx53loco board, so bump to this kernel version.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

configs/mx53loco_defconfig

@@ -28,7 +28,7 @@ BR2_TARGET_UBOOT_FORMAT_IMX=y
 # Kernel
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.17"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.17.4"
 BR2_LINUX_KERNEL_DEFCONFIG="imx_v6_v7"
 BR2_LINUX_KERNEL_DTS_SUPPORT=y
 BR2_LINUX_KERNEL_INTREE_DTS_NAME="imx53-qsb imx53-qsrb"