pwm: Remove a redundant error message when devm_request_and_ioremap fails

The implementation in devm_request_and_ioremap() already shows error message,
so no need to show dev_err again if devm_request_and_ioremap() fails.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Philip, Avinash <avinashphilip@ti.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>