doc: nvmem: Remove references to regmap

Since commit 795ddd1 ("nvmem: core: remove regmap dependency"),
nvmem devices do not use the regmap API. Remove references to it from
the documentation.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151527.17216-11-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/driver-api/nvmem.rst

@@ -26,9 +26,7 @@ was a rather big abstraction leak.
 
 This framework aims at solve these problems. It also introduces DT
 representation for consumer devices to go get the data they require (MAC
-Addresses, SoC/Revision ID, part numbers, and so on) from the NVMEMs. This
-framework is based on regmap, so that most of the abstraction available in
-regmap can be reused, across multiple types of buses.
+Addresses, SoC/Revision ID, part numbers, and so on) from the NVMEMs.
 
 NVMEM Providers
 +++++++++++++++
@@ -60,9 +58,6 @@ For example, a simple qfprom case::
 	...
   }
 
-It is mandatory that the NVMEM provider has a regmap associated with its
-struct device. Failure to do would return error code from nvmem_register().
-
 Users of board files can define and register nvmem cells using the
 nvmem_cell_table struct::