pwm: remove unneeded ifdef CONFIG_DM_PWM ... endif

Both CONFIG_PWM_TEGRA and CONFIG_PWM_EXYNOS depend on CONFIG_DM_PWM,
i.e. they are already guarded by Kconfig correctly.  Remove unneeded
ifdef CONFIG_DM_PWM ... endif.

While we are here, let's tidy up alignment and sort the lines
alphabetically in Makefile.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>