The device tree parsing code for the STM32 platform is using its own FDT
helper functions, some of them being rather generic.
In particular the existing fdt_read_uint32_array() implementation is now
almost identical to the new generic code in fdt_wrappers.c, so we can
remove the ST specific version and adjust the existing callers.

Compared to the original ST implementation the new version takes a
pointer to the DTB as the first argument, and also swaps the order of
the number of cells and the pointer.

Change-Id: Id06b0f1ba4db1ad1f733be40e82c34f46638551a
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

Those functions are generic for parsing nodes from device tree
hence could be located in generic source file.

The oscillators description structure is also moved to STM32MP1 clock
driver, as it is no more used in stm32mp1_clkfunc and cannot be in a
generic file.

Change-Id: I93ba74f4eea916440fef9b160d306af1b39f17c6
Signed-off-by: Yann Gautier <yann.gautier@st.com>

Create a new file stm32mp_clkfunc.c to put functions that could be common
between several platforms.

Change-Id: Ica915c796b162b2345056b33328acc05035a242c
Signed-off-by: Yann Gautier <yann.gautier@st.com>