dts: arm: st: stm32h5: fix flash erase timing

According to the datasheet the flash erase timing is
typically 2ms, and max 10ms.

H503: DS14053 Rev 4: section 5.3.10, table 45, t_erase_max=10ms
H562/H563: DS14258 Rev 6: section 5.3.11, table 51, t_erase_max=10ms

Signed-off-by: Thomas Stranger <thomas.stranger@outlook.com>