wifi: iwlwifi: mvm: Fix a memory corruption issue

A few lines above, space is kzalloc()'ed for:
	sizeof(struct iwl_nvm_data) +
	sizeof(struct ieee80211_channel) +
	sizeof(struct ieee80211_rate)

'mvm->nvm_data' is a 'struct iwl_nvm_data', so it is fine.

At the end of this structure, there is the 'channels' flex array.
Each element is of type 'struct ieee80211_channel'.
So only 1 element is allocated in this array.

When doing:
  mvm->nvm_data->bands[0].channels = mvm->nvm_data->channels;
We point at the first element of the 'channels' flex array.
So this is fine.

However, when doing:
  mvm->nvm_data->bands[0].bitrates =
			(void *)((u8 *)mvm->nvm_data->channels + 1);
because of the "(u8 *)" cast, we add only 1 to the address of the beginning
of the flex array.

It is likely that we want point at the 'struct ieee80211_rate' allocated
just after.

Remove the spurious casting so that the pointer arithmetic works as
expected.

Fixes: 8ca151b5

 ("iwlwifi: add the MVM driver")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/23f0ec986ef1529055f4f93dcb3940a6cf8d9a94.1690143750.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Johannes Berg <johannes.berg@intel.com>