configs/qemu: use zImage for sh4/sh4eb samples

The default for ARM was changed to zImage in 5c67cb1d, however the
sh4/sh4eb sample configs were updated to switch to uImage in error,
hence end up building uImage which doesn't work with Qemu.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
[Thomas: fix commit log.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

configs/qemu_sh4_r2d_defconfig

@@ -19,3 +19,4 @@ BR2_LINUX_KERNEL_CUSTOM_VERSION=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.5"
 BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
 BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/sh4-r2d/linux-4.5.config"
+BR2_LINUX_KERNEL_ZIMAGE=y

configs/qemu_sh4eb_r2d_defconfig

@@ -18,3 +18,4 @@ BR2_LINUX_KERNEL_CUSTOM_VERSION=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.5"
 BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
 BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/sh4eb-r2d/linux-4.5.config"
+BR2_LINUX_KERNEL_ZIMAGE=y