[PATCH v3] mips: bcm63xx: add support for clk_get_parent()

[Randy Dunlap <rdunlap@infradead.org>]

BCM63XX selects HAVE_LEGACY_CLK but does not provide/support
clk_get_parent(), so add a simple implementation of that
function so that callers of it will build without errors.

Fixes these build errors:

mips-linux-ld: drivers/iio/adc/ingenic-adc.o: in function `jz4770_adc_init_clk_div':
ingenic-adc.c:(.text+0xe4): undefined reference to `clk_get_parent'
mips-linux-ld: drivers/iio/adc/ingenic-adc.o: in function `jz4725b_adc_init_clk_div':
ingenic-adc.c:(.text+0x1b8): undefined reference to `clk_get_parent'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Artur Rojek <contact@artur-rojek.eu>
Cc: Paul Cercueil <paul@crapouillou.net>
Cc: linux-mips@vger.kernel.org
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: linux-iio@vger.kernel.org
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: Jonas Gorski <jonas.gorski@gmail.com>
---
v1 and v2 were:
[PATCH] iio/adc: ingenic: fix (MIPS) ingenic-adc build errors
Fixes: 1a78daea107d ("IIO: add Ingenic JZ47xx ADC driver.")

 arch/mips/bcm63xx/clk.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- linux-next-20211112.orig/arch/mips/bcm63xx/clk.c
+++ linux-next-20211112/arch/mips/bcm63xx/clk.c
@@ -381,6 +381,13 @@ void clk_disable(struct clk *clk)
 
 EXPORT_SYMBOL(clk_disable);
 
+struct clk *clk_get_parent(struct clk *clk)
+{
+	return NULL;
+}
+
+EXPORT_SYMBOL(clk_get_parent);
+
 unsigned long clk_get_rate(struct clk *clk)
 {
 	if (!clk)