[l1] fix whitespace and missing license info

Earlier additions to the L1 support were not correctly using linux
coding guidelines as specified in /HACKING.

Some examples were also missing license information.
[l1] PWR: fix style for common code

Code added for L1 to support the PWR Control block didn't properly
follow the HACKING_COMMON_DOC guidelines.  The naming was wrong, and
some headers were missing.  This commit has no functional changes, it
only addresses the style and structure problems.
[l1] Update to newest ref man definitions

Support for the Medium+ and High density parts, mostly by way of extra
irqs and register definitions.
[l1] rcc: support MSI clocking

Some new definitions and helpers.  Main change really that the list of
preconfigured clock configs is no longer restricted to HSI/PLL
[stm32] Support the "new" BCD style RTC peripheral

Add the register definitions and some of the most basic helper functions
for the new style BCD RTC module found on the F2, F4, L1, F3 and F0.

This tries to keep as close to HACKING_COMMON_DOC as possible, while
maintaining sane names.
Add examples making use of the RTC

Add an example using the RTC to help with a lower power design.  This is
a sister example to the existing "button-irq-printf", which is
functionally identical, but uses far less power.

There's more tricks that can be done to lower the power even further,
but this shows a few of the early steps that can be done, using the RTC
wakeup instead of a timer.