dts: arm: st: Fix incorrect memory mapping and size for STM32L475Xe

This commit updates the SRAM configuration in the STM32L475 device tree:

- `sram0` size reduced from 128K to 96K.
- `sram1` added with 32K.

These changes correct memory settings to prevent initialization failures.

Signed-off-by: Tianshuang Ke <qinyun575@gmail.com>