docs: drivers: fix some warnings at base/platform.c when building docs

Currrently, two warnings are generated when building docs:

	./drivers/base/platform.c:136: WARNING: Unexpected indentation.
	./drivers/base/platform.c:214: WARNING: Unexpected indentation.

As examples are code blocks, they should use "::" markup. However,

	Example::

Is currently interpreted as a new section.

While we could fix kernel-doc to accept such new syntax, it is
easier to just replace it with:

	For Example::
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/564273815a76136fb5e453969b1012a786d99e28.1586881715.git.mchehab+huawei@kernel.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

drivers/base/platform.c

@@ -147,7 +147,8 @@ EXPORT_SYMBOL_GPL(devm_platform_ioremap_resource_byname);
  * request_irq() APIs. This is the same as platform_get_irq(), except that it
  * does not print an error message if an IRQ can not be obtained.
  *
- * Example:
+ * For example::
+ *
  *		int irq = platform_get_irq_optional(pdev, 0);
  *		if (irq < 0)
  *			return irq;
@@ -226,7 +227,8 @@ EXPORT_SYMBOL_GPL(platform_get_irq_optional);
  * IRQ fails. Device drivers should check the return value for errors so as to
  * not pass a negative integer value to the request_irq() APIs.
  *
- * Example:
+ * For example::
+ *
  *		int irq = platform_get_irq(pdev, 0);
  *		if (irq < 0)
  *			return irq;