Documentation: fix few typos and clarifications for the firmware loader

Fix a few typos, and clarify a few sentences.

Reviewed-by: Kees Cook <[e-mail]>
Signed-off-by: Luis R. Rodriguez <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/driver-api/firmware/fallback-mechanisms.rst

···
   * /sys/$DEVPATH/data
 
 To upload firmware you will echo 1 onto the loading file to indicate
-you are loading firmware. You then cat the firmware into the data file,
+you are loading firmware. You then write the firmware into the data file,
 and you notify the kernel the firmware is ready by echo'ing 0 onto
 the loading file.
 
···
 distributions today disable CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
 
 Refer to do_firmware_uevent() for details of the kobject event variables
-setup. Variables passwdd with a kobject add event:
+setup. The variables currently passed to userspace with a "kobject add"
+event are:
 
 * FIRMWARE=firmware name
 * TIMEOUT=timeout value

Documentation/driver-api/firmware/firmware_cache.rst

···
 * If an asynchronous call is used the firmware cache is only set up for a
   device if if the second argument (uevent) to request_firmware_nowait() is
   true. When uevent is true it requests that a kobject uevent be sent to
-  userspace for the firmware request. For details refer to the Fackback
-  mechanism documented below.
+  userspace for the firmware request through the sysfs fallback mechanism
+  if the firmware file is not found.
 
 * If the firmware cache is determined to be needed as per the above two
   criteria the firmware cache is setup by adding a devres entry for the