Disable LSE for MTB_USI_WM_BN_BM_22
Disable LSE for MTB_USI_WM_BN_BM_22

Current MTB_USI_WM_BN_BM_22 modules do not have OSC32_IN connected, so
external xtal is not in use.

kjbracey-arm/mbed,betzw/mbed-os,kjbracey-arm/mbed,c1728p9/mbed-os,mbedmicro/mbed,betzw/mbed-os,mbedmicro/mbed,mbedmicro/mbed,andcor02/mbed-os,betzw/mbed-os,mbedmicro/mbed,betzw/mbed-os,c1728p9/mbed-os,kjbracey-arm/mbed,andcor02/mbed-os,c1728p9/mbed-os,andcor02/mbed-os,c1728p9/mbed-os,betzw/mbed-os,mbedmicro/mbed,andcor02/mbed-os,kjbracey-arm/mbed,andcor02/mbed-os,c1728p9/mbed-os,betzw/mbed-os,andcor02/mbed-os,c1728p9/mbed-os