configs/qemu: enable tmpfs for microblaze

Otherwise the tmpfs-backed filesystems fail:
mount: mounting tmpfs on /dev/shm failed: Invalid argument
mount: mounting tmpfs on /tmp failed: Invalid argument
mount: mounting tmpfs on /run failed: Invalid argument

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

board/qemu/microblazebe-mmu/linux-4.3.config

@@ -17,3 +17,4 @@ CONFIG_XILINX_EMACLITE=y
 CONFIG_SERIAL_UARTLITE=y
 CONFIG_SERIAL_UARTLITE_CONSOLE=y
 # CONFIG_VGA_CONSOLE is not set
+CONFIG_TMPFS=y

board/qemu/microblazeel-mmu/linux-4.3.config

@@ -16,3 +16,4 @@ CONFIG_XILINX_EMACLITE=y
 CONFIG_SERIAL_UARTLITE=y
 CONFIG_SERIAL_UARTLITE_CONSOLE=y
 # CONFIG_VGA_CONSOLE is not set
+CONFIG_TMPFS=y