There is no manufacturer's recommended value.
If the resistance constant is increased, the signal waveform will become dull, and if the constant is decreased, the current consumption will increase. The concept is the same as general pull-up/pull-down.
The EFM32 GPIO has a built-in pull-up/pull-down of about 40kΩ, so depending on the application, an external pull-up/pull-down may not be necessary.

Note that if you use an external pull-up, depending on the pull-up voltage you choose, it is possible that voltage will be applied to the IO pin before the EFM32 is powered. Since the device may be damaged, please also refer to another topic (Is it okay to input a signal from the outside when the power is not supplied?).