fpga: zynq-fpga: Rename 'timeout' variable as 'time_left'

There is a confusing pattern in the kernel to use a variable named
'timeout' to store the result of wait_for_completion_timeout() causing
patterns like:

        timeout = wait_for_completion_timeout(...)
        if (!timeout) return -ETIMEDOUT;

with all kinds of permutations. Use 'time_left' as a variable to make the
code self explaining.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Michal Simek <michal.simek@amd.com>
Acked-by: Xu Yilun <yilun.xu@intel.com>
Link: https://lore.kernel.org/r/20240729104319.2658-2-wsa+renesas@sang-engineering.com


Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>