flash/stm32l4x: do not report bank mode before probing [FIX]

flash/stm32l4x: do not report bank mode before probing [FIX]

in line 1391, get_stm32l4_bank_type_str(bank) will always output the same
value "Flash single" since the variable stm32l4_info->dual_bank_mode is false
by default, stm32l4_info->dual_bank_mode will be set correctly afterward
in the switch case at line 1467

thus the need to remove the usage of get_stm32l4_bank_type_str(bank) before
stm32l4_info->dual_bank_mode initialization.

Fixes: 64c2e03b23d9 ("flash/nor: improved API of flash_driver.info & fixed buffer overruns")
Change-Id: Ia8dc7e144e0ded6143682eb514c247f27859ff81
Signed-off-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6411
Reviewed-by: Oleksij Rempel <linux@rempel-privat.de>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins