misc: set error code when devm_kstrdup fails

In function sram_reserve_regions(), the value of return variable ret
should be negative on failures. However, the value of ret may be 0 even
if the call to devm_kstrdup() returns a NULL pointer. This patch
explicitly assigns "-ENOMEM" to ret on the path that devm_kstrdup()
fails.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=188651



Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>