iwlwifi: Fix memory leaks in error handling path

Should an error occur (invalid TLV len or memory allocation failure), the
memory already allocated in 'reduce_power_data' should be freed before
returning, otherwise it is leaking.

Fixes: 9dad325f ("iwlwifi: support loading the reduced power table from UEFI")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1504cd7d842d13ddb8244e18004523128d5c9523.1636615284.git.christophe.jaillet@wanadoo.fr