lib: fix typos in Kconfig

There are trivial typos in the Kconfig file. Fixed them.
Also, fixed grammar in the descriptions with typos.

Fixes: d56b4b19 ("configs: Migrate RBTREE, LZO, CMD_MTDPARTS, CMD_UBI and CMD_UBIFS")
Fixes: 7264f292 ("spl: fit: Eanble GZIP support for image decompression")
Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@foundries.io>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>