MIPS: JZ4740: Don't select HAVE_PWM

MIPS: JZ4740: Don't select HAVE_PWM

The HAVE_PWM symbol is only for legacy platforms that provide the PWM
API without using the generic framework. The jz4740 platform uses the
generic PWM framework, after the commit "f6b8a57 pwm: Add Ingenic
JZ4740 support".

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6525/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>