soc: xilinx: use a properly named field instead of flags

Instead of defining a flags field and a single bit in this field to
signal that a PM node has been requested, use a boolean field with a
descriptive name.

No functional change, but using a proper name instead of flags makes the
code easier to read.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Rajan Vaja <rajan.vaja@xilinx.com>
Link: https://lore.kernel.org/r/20210825150313.4033156-4-m.tretter@pengutronix.de


Signed-off-by: Michal Simek <michal.simek@xilinx.com>