ARM: at91/defconfig: remove at91 cpuidle

Remove the use of AT91 CPUIDLE as it behaves badly with Ethernet benchmarks and
can lock the network interface.

Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>

Author: noglitch

arch/arm/configs/at91_dt_defconfig

@@ -26,6 +26,7 @@ CONFIG_ZBOOT_ROM_BSS=0x0
 CONFIG_CMDLINE="console=ttyS0,115200 initrd=0x21100000,25165824 root=/dev/ram0 rw"
 CONFIG_KEXEC=y
 CONFIG_CPU_IDLE=y
+# CONFIG_ARM_AT91_CPUIDLE is not set
 # CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS is not set
 CONFIG_PM_DEBUG=y
 CONFIG_PM_ADVANCED_DEBUG=y