phy: cadence: Sierra: Add array of input clocks in "struct cdns_sierra_phy"

Instead of having separate structure members for each input clock, add
an array for the input clocks within "struct cdns_sierra_phy". This is
in preparation for adding more input clocks required for supporting
additional clock combination.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Reviewed-by: Swapnil Jakhade <sjakhade@cadence.com>
Link: https://lore.kernel.org/r/20210319124128.13308-10-kishon@ti.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>