zynqmp: Save "bootseq" environment variable in decimal format

zynqmp: Save "bootseq" environment variable in decimal format

In U-Boot, most of mmc releated commands uses decimal value in arguments, like
"mmc dev ${bootseq}" or "bootargs=root=/dev/mmcblk${bootseq}p2". In order to
improve compatibilities, export "bootseq" number to environment variable in
decimal format instead of hex.

Signed-off-by: Benjamin Szőke <egyszeregy@freemail.hu>
Link: https://lore.kernel.org/r/20250204205617.1238-1-egyszeregy@freemail.hu
Signed-off-by: Michal Simek <michal.simek@amd.com>