net: stmmac: est: Fix GCL bounds checks

Fix the bounds checks for the hw supported maximum GCL entry
count and gate interval time.

Fixes: b60189e0 ("net: stmmac: Integrate EST with TAPRIO scheduler API")
Signed-off-by: Rohan G Thomas <rohan.g.thomas@altera.com>
Reviewed-by: Matthew Gerlach <matthew.gerlach@altera.com>
Link: https://patch.msgid.link/20251028-qbv-fixes-v4-3-26481c7634e3@altera.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>