powerpc/mpc5xxx: Switch mpc5xxx_get_bus_frequency() to use fwnode

Switch mpc5xxx_get_bus_frequency() to use fwnode in order to help
cleaning up other parts of the kernel from OF specific code.

No functional change intended.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Chris Packham <chris.packham@alliedtelesis.co.nz> # for i2c-mpc
Acked-by: Wolfram Sang <wsa@kernel.org> # for the I2C part
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de> # for mscan/mpc5xxx_can
Acked-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220507100147.5802-2-andriy.shevchenko@linux.intel.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 40

Based on 1 normalized pattern(s):

this is free software you can redistribute it and or modify it under
the terms of the gnu general public license as published by the free
software foundation either version 2 of the license or at your
option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 14 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190520170857.915677517@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

powerpc/5xxx: Add common mpc5xxx_get_bus_frequency() function

So far, MPC512x used mpc512x_find_ips_freq() to get the bus frequency,
while MPC52xx used mpc52xx_find_ipb_freq(). Despite the different
clock names (IPS vs. IPB) the code was identical.

Use common code for both processor families.

Signed-off-by: Wolfgang Denk <wd@denx.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>