arm64: remove duplicate PWM entry in defconfig

We merged two patches that both enabled CONFIG_PWM, leading to a harmless
warning:

arch/arm64/configs/defconfig:352:warning: override: reassigning to symbol PWM

This removes one of the two identical lines to avoid the warning.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm64/configs/defconfig

@@ -346,7 +346,6 @@ CONFIG_ARM_SCPI_PROTOCOL=y
 CONFIG_ACPI=y
 CONFIG_IIO=y
 CONFIG_EXYNOS_ADC=y
-CONFIG_PWM=y
 CONFIG_PWM_SAMSUNG=y
 CONFIG_EXT2_FS=y
 CONFIG_EXT3_FS=y