clocksource/drivers/samsung_pwm: Minor whitespace cleanup

Cleanup the code to be slightly more readable and follow coding
convention - only whitespace.  This fixes checkpatch warnings:

  WARNING: Block comments should align the * on each line
  WARNING: please, no space before tabs
  WARNING: Missing a blank line after declarations
  CHECK: Alignment should match open parenthesis

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210506202729.157260-1-krzysztof.kozlowski@canonical.com