isa: Remove unnecessary checks

The isa_dev->dev.platform_data is initialized with incoming
parameter isa_driver. After it isa_dev->dev.platform_data is
checked for NULL, but incoming parameter isa_driver is not
NULL since it is dereferenced many times before this check.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Vladislav Efanov <VEfanov@ispras.ru>
Acked-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/20230517125025.434005-1-VEfanov@ispras.ru


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>